tty/powerpc: introduce the ePAPR embedded hypervisor byte channel driver
The ePAPR embedded hypervisor specification provides an API for "byte channels", which are serial-like virtual devices for sending and receiving streams of bytes. This driver provides Linux kernel support for byte channels via three distinct interfaces: 1) An early-console (udbg) driver. This provides early console output through a byte channel. The byte channel handle must be specified in a Kconfig option. 2) A normal console driver. Output is sent to the byte channel designated for stdout in the device tree. The console driver is for handling kernel printk calls. 3) A tty driver, which is used to handle user-space input and output. The byte channel used for the console is designated as the default tty. Signed-off-by: Timur Tabi <timur@freescale.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Timur Tabi
Greg Kroah-Hartman
parent
fcb8ce5cfe
commit
dcd83aaff1
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@ -54,6 +54,7 @@ extern void __init udbg_init_40x_realmode(void);
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extern void __init udbg_init_cpm(void);
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extern void __init udbg_init_cpm(void);
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extern void __init udbg_init_usbgecko(void);
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extern void __init udbg_init_usbgecko(void);
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extern void __init udbg_init_wsp(void);
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extern void __init udbg_init_wsp(void);
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extern void __init udbg_init_ehv_bc(void);
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#endif /* __KERNEL__ */
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_UDBG_H */
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#endif /* _ASM_POWERPC_UDBG_H */
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@ -67,6 +67,8 @@ void __init udbg_early_init(void)
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udbg_init_usbgecko();
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udbg_init_usbgecko();
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#elif defined(CONFIG_PPC_EARLY_DEBUG_WSP)
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#elif defined(CONFIG_PPC_EARLY_DEBUG_WSP)
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udbg_init_wsp();
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udbg_init_wsp();
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#elif defined(CONFIG_PPC_EARLY_DEBUG_EHV_BC)
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udbg_init_ehv_bc();
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#endif
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#endif
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#ifdef CONFIG_PPC_EARLY_DEBUG
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#ifdef CONFIG_PPC_EARLY_DEBUG
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@ -350,3 +350,37 @@ config TRACE_SINK
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If you select this option, you need to select
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If you select this option, you need to select
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"Trace data router for MIPI P1149.7 cJTAG standard".
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"Trace data router for MIPI P1149.7 cJTAG standard".
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config PPC_EPAPR_HV_BYTECHAN
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tristate "ePAPR hypervisor byte channel driver"
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depends on PPC
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help
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This driver creates /dev entries for each ePAPR hypervisor byte
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channel, thereby allowing applications to communicate with byte
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channels as if they were serial ports.
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config PPC_EARLY_DEBUG_EHV_BC
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bool "Early console (udbg) support for ePAPR hypervisors"
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depends on PPC_EPAPR_HV_BYTECHAN
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help
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Select this option to enable early console (a.k.a. "udbg") support
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via an ePAPR byte channel. You also need to choose the byte channel
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handle below.
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config PPC_EARLY_DEBUG_EHV_BC_HANDLE
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int "Byte channel handle for early console (udbg)"
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depends on PPC_EARLY_DEBUG_EHV_BC
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default 0
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help
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If you want early console (udbg) output through a byte channel,
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specify the handle of the byte channel to use.
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For this to work, the byte channel driver must be compiled
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in-kernel, not as a module.
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Note that only one early console driver can be enabled, so don't
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enable any others if you enable this one.
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If the number you specify is not a valid byte channel handle, then
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there simply will be no early console output. This is true also
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if you don't boot under a hypervisor at all.
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@ -26,5 +26,6 @@ obj-$(CONFIG_ROCKETPORT) += rocket.o
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obj-$(CONFIG_SYNCLINK_GT) += synclink_gt.o
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obj-$(CONFIG_SYNCLINK_GT) += synclink_gt.o
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obj-$(CONFIG_SYNCLINKMP) += synclinkmp.o
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obj-$(CONFIG_SYNCLINKMP) += synclinkmp.o
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obj-$(CONFIG_SYNCLINK) += synclink.o
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obj-$(CONFIG_SYNCLINK) += synclink.o
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obj-$(CONFIG_PPC_EPAPR_HV_BYTECHAN) += ehv_bytechan.o
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obj-y += ipwireless/
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obj-y += ipwireless/
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@ -0,0 +1,888 @@
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/* ePAPR hypervisor byte channel device driver
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*
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* Copyright 2009-2011 Freescale Semiconductor, Inc.
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*
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* Author: Timur Tabi <timur@freescale.com>
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*
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* This file is licensed under the terms of the GNU General Public License
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* version 2. This program is licensed "as is" without any warranty of any
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* kind, whether express or implied.
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*
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* This driver support three distinct interfaces, all of which are related to
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* ePAPR hypervisor byte channels.
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*
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* 1) An early-console (udbg) driver. This provides early console output
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* through a byte channel. The byte channel handle must be specified in a
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* Kconfig option.
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*
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* 2) A normal console driver. Output is sent to the byte channel designated
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* for stdout in the device tree. The console driver is for handling kernel
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* printk calls.
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*
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* 3) A tty driver, which is used to handle user-space input and output. The
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* byte channel used for the console is designated as the default tty.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/err.h>
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#include <linux/interrupt.h>
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#include <linux/fs.h>
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#include <linux/poll.h>
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#include <asm/epapr_hcalls.h>
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#include <linux/of.h>
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#include <linux/platform_device.h>
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#include <linux/cdev.h>
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#include <linux/console.h>
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#include <linux/tty.h>
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#include <linux/tty_flip.h>
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#include <linux/circ_buf.h>
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#include <asm/udbg.h>
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/* The size of the transmit circular buffer. This must be a power of two. */
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#define BUF_SIZE 2048
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/* Per-byte channel private data */
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struct ehv_bc_data {
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struct device *dev;
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struct tty_port port;
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uint32_t handle;
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unsigned int rx_irq;
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unsigned int tx_irq;
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spinlock_t lock; /* lock for transmit buffer */
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unsigned char buf[BUF_SIZE]; /* transmit circular buffer */
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unsigned int head; /* circular buffer head */
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unsigned int tail; /* circular buffer tail */
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int tx_irq_enabled; /* true == TX interrupt is enabled */
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};
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/* Array of byte channel objects */
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static struct ehv_bc_data *bcs;
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/* Byte channel handle for stdout (and stdin), taken from device tree */
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static unsigned int stdout_bc;
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/* Virtual IRQ for the byte channel handle for stdin, taken from device tree */
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static unsigned int stdout_irq;
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/**************************** SUPPORT FUNCTIONS ****************************/
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/*
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* Enable the transmit interrupt
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*
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* Unlike a serial device, byte channels have no mechanism for disabling their
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* own receive or transmit interrupts. To emulate that feature, we toggle
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* the IRQ in the kernel.
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*
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* We cannot just blindly call enable_irq() or disable_irq(), because these
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* calls are reference counted. This means that we cannot call enable_irq()
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* if interrupts are already enabled. This can happen in two situations:
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*
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* 1. The tty layer makes two back-to-back calls to ehv_bc_tty_write()
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* 2. A transmit interrupt occurs while executing ehv_bc_tx_dequeue()
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*
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* To work around this, we keep a flag to tell us if the IRQ is enabled or not.
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*/
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static void enable_tx_interrupt(struct ehv_bc_data *bc)
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{
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if (!bc->tx_irq_enabled) {
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enable_irq(bc->tx_irq);
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bc->tx_irq_enabled = 1;
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}
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}
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static void disable_tx_interrupt(struct ehv_bc_data *bc)
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{
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if (bc->tx_irq_enabled) {
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disable_irq_nosync(bc->tx_irq);
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bc->tx_irq_enabled = 0;
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}
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}
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/*
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* find the byte channel handle to use for the console
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*
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* The byte channel to be used for the console is specified via a "stdout"
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* property in the /chosen node.
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*
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* For compatible with legacy device trees, we also look for a "stdout" alias.
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*/
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static int find_console_handle(void)
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{
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struct device_node *np, *np2;
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const char *sprop = NULL;
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const uint32_t *iprop;
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np = of_find_node_by_path("/chosen");
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if (np)
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sprop = of_get_property(np, "stdout-path", NULL);
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if (!np || !sprop) {
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of_node_put(np);
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np = of_find_node_by_name(NULL, "aliases");
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if (np)
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sprop = of_get_property(np, "stdout", NULL);
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}
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if (!sprop) {
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of_node_put(np);
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return 0;
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}
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/* We don't care what the aliased node is actually called. We only
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* care if it's compatible with "epapr,hv-byte-channel", because that
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* indicates that it's a byte channel node. We use a temporary
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* variable, 'np2', because we can't release 'np' until we're done with
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* 'sprop'.
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*/
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np2 = of_find_node_by_path(sprop);
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of_node_put(np);
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np = np2;
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if (!np) {
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pr_warning("ehv-bc: stdout node '%s' does not exist\n", sprop);
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return 0;
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}
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/* Is it a byte channel? */
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if (!of_device_is_compatible(np, "epapr,hv-byte-channel")) {
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of_node_put(np);
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return 0;
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}
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stdout_irq = irq_of_parse_and_map(np, 0);
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if (stdout_irq == NO_IRQ) {
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pr_err("ehv-bc: no 'interrupts' property in %s node\n", sprop);
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of_node_put(np);
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return 0;
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}
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/*
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* The 'hv-handle' property contains the handle for this byte channel.
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*/
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iprop = of_get_property(np, "hv-handle", NULL);
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if (!iprop) {
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pr_err("ehv-bc: no 'hv-handle' property in %s node\n",
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np->name);
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of_node_put(np);
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return 0;
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}
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stdout_bc = be32_to_cpu(*iprop);
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of_node_put(np);
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return 1;
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}
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/*************************** EARLY CONSOLE DRIVER ***************************/
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#ifdef CONFIG_PPC_EARLY_DEBUG_EHV_BC
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/*
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* send a byte to a byte channel, wait if necessary
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*
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* This function sends a byte to a byte channel, and it waits and
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* retries if the byte channel is full. It returns if the character
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* has been sent, or if some error has occurred.
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*
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*/
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static void byte_channel_spin_send(const char data)
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{
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int ret, count;
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do {
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count = 1;
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ret = ev_byte_channel_send(CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE,
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&count, &data);
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} while (ret == EV_EAGAIN);
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}
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/*
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* The udbg subsystem calls this function to display a single character.
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* We convert CR to a CR/LF.
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*/
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static void ehv_bc_udbg_putc(char c)
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{
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if (c == '\n')
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byte_channel_spin_send('\r');
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byte_channel_spin_send(c);
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}
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/*
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* early console initialization
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*
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* PowerPC kernels support an early printk console, also known as udbg.
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* This function must be called via the ppc_md.init_early function pointer.
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* At this point, the device tree has been unflattened, so we can obtain the
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* byte channel handle for stdout.
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*
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* We only support displaying of characters (putc). We do not support
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* keyboard input.
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*/
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void __init udbg_init_ehv_bc(void)
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{
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unsigned int rx_count, tx_count;
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unsigned int ret;
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/* Check if we're running as a guest of a hypervisor */
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if (!(mfmsr() & MSR_GS))
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return;
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/* Verify the byte channel handle */
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ret = ev_byte_channel_poll(CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE,
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&rx_count, &tx_count);
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if (ret)
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return;
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udbg_putc = ehv_bc_udbg_putc;
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register_early_udbg_console();
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udbg_printf("ehv-bc: early console using byte channel handle %u\n",
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CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE);
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}
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#endif
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/****************************** CONSOLE DRIVER ******************************/
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static struct tty_driver *ehv_bc_driver;
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/*
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* Byte channel console sending worker function.
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*
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* For consoles, if the output buffer is full, we should just spin until it
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* clears.
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*/
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static int ehv_bc_console_byte_channel_send(unsigned int handle, const char *s,
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unsigned int count)
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{
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unsigned int len;
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int ret = 0;
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while (count) {
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len = min_t(unsigned int, count, EV_BYTE_CHANNEL_MAX_BYTES);
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do {
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ret = ev_byte_channel_send(handle, &len, s);
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} while (ret == EV_EAGAIN);
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count -= len;
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s += len;
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}
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return ret;
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}
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/*
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* write a string to the console
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*
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* This function gets called to write a string from the kernel, typically from
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* a printk(). This function spins until all data is written.
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*
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* We copy the data to a temporary buffer because we need to insert a \r in
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* front of every \n. It's more efficient to copy the data to the buffer than
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* it is to make multiple hcalls for each character or each newline.
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*/
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static void ehv_bc_console_write(struct console *co, const char *s,
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unsigned int count)
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{
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unsigned int handle = (unsigned int)co->data;
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char s2[EV_BYTE_CHANNEL_MAX_BYTES];
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unsigned int i, j = 0;
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char c;
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for (i = 0; i < count; i++) {
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c = *s++;
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if (c == '\n')
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s2[j++] = '\r';
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s2[j++] = c;
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||||||
|
if (j >= (EV_BYTE_CHANNEL_MAX_BYTES - 1)) {
|
||||||
|
if (ehv_bc_console_byte_channel_send(handle, s2, j))
|
||||||
|
return;
|
||||||
|
j = 0;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
if (j)
|
||||||
|
ehv_bc_console_byte_channel_send(handle, s2, j);
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* When /dev/console is opened, the kernel iterates the console list looking
|
||||||
|
* for one with ->device and then calls that method. On success, it expects
|
||||||
|
* the passed-in int* to contain the minor number to use.
|
||||||
|
*/
|
||||||
|
static struct tty_driver *ehv_bc_console_device(struct console *co, int *index)
|
||||||
|
{
|
||||||
|
*index = co->index;
|
||||||
|
|
||||||
|
return ehv_bc_driver;
|
||||||
|
}
|
||||||
|
|
||||||
|
static struct console ehv_bc_console = {
|
||||||
|
.name = "ttyEHV",
|
||||||
|
.write = ehv_bc_console_write,
|
||||||
|
.device = ehv_bc_console_device,
|
||||||
|
.flags = CON_PRINTBUFFER | CON_ENABLED,
|
||||||
|
};
|
||||||
|
|
||||||
|
/*
|
||||||
|
* Console initialization
|
||||||
|
*
|
||||||
|
* This is the first function that is called after the device tree is
|
||||||
|
* available, so here is where we determine the byte channel handle and IRQ for
|
||||||
|
* stdout/stdin, even though that information is used by the tty and character
|
||||||
|
* drivers.
|
||||||
|
*/
|
||||||
|
static int __init ehv_bc_console_init(void)
|
||||||
|
{
|
||||||
|
if (!find_console_handle()) {
|
||||||
|
pr_debug("ehv-bc: stdout is not a byte channel\n");
|
||||||
|
return -ENODEV;
|
||||||
|
}
|
||||||
|
|
||||||
|
#ifdef CONFIG_PPC_EARLY_DEBUG_EHV_BC
|
||||||
|
/* Print a friendly warning if the user chose the wrong byte channel
|
||||||
|
* handle for udbg.
|
||||||
|
*/
|
||||||
|
if (stdout_bc != CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE)
|
||||||
|
pr_warning("ehv-bc: udbg handle %u is not the stdout handle\n",
|
||||||
|
CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE);
|
||||||
|
#endif
|
||||||
|
|
||||||
|
ehv_bc_console.data = (void *)stdout_bc;
|
||||||
|
|
||||||
|
/* add_preferred_console() must be called before register_console(),
|
||||||
|
otherwise it won't work. However, we don't want to enumerate all the
|
||||||
|
byte channels here, either, since we only care about one. */
|
||||||
|
|
||||||
|
add_preferred_console(ehv_bc_console.name, ehv_bc_console.index, NULL);
|
||||||
|
register_console(&ehv_bc_console);
|
||||||
|
|
||||||
|
pr_info("ehv-bc: registered console driver for byte channel %u\n",
|
||||||
|
stdout_bc);
|
||||||
|
|
||||||
|
return 0;
|
||||||
|
}
|
||||||
|
console_initcall(ehv_bc_console_init);
|
||||||
|
|
||||||
|
/******************************** TTY DRIVER ********************************/
|
||||||
|
|
||||||
|
/*
|
||||||
|
* byte channel receive interupt handler
|
||||||
|
*
|
||||||
|
* This ISR is called whenever data is available on a byte channel.
|
||||||
|
*/
|
||||||
|
static irqreturn_t ehv_bc_tty_rx_isr(int irq, void *data)
|
||||||
|
{
|
||||||
|
struct ehv_bc_data *bc = data;
|
||||||
|
struct tty_struct *ttys = tty_port_tty_get(&bc->port);
|
||||||
|
unsigned int rx_count, tx_count, len;
|
||||||
|
int count;
|
||||||
|
char buffer[EV_BYTE_CHANNEL_MAX_BYTES];
|
||||||
|
int ret;
|
||||||
|
|
||||||
|
/* ttys could be NULL during a hangup */
|
||||||
|
if (!ttys)
|
||||||
|
return IRQ_HANDLED;
|
||||||
|
|
||||||
|
/* Find out how much data needs to be read, and then ask the TTY layer
|
||||||
|
* if it can handle that much. We want to ensure that every byte we
|
||||||
|
* read from the byte channel will be accepted by the TTY layer.
|
||||||
|
*/
|
||||||
|
ev_byte_channel_poll(bc->handle, &rx_count, &tx_count);
|
||||||
|
count = tty_buffer_request_room(ttys, rx_count);
|
||||||
|
|
||||||
|
/* 'count' is the maximum amount of data the TTY layer can accept at
|
||||||
|
* this time. However, during testing, I was never able to get 'count'
|
||||||
|
* to be less than 'rx_count'. I'm not sure whether I'm calling it
|
||||||
|
* correctly.
|
||||||
|
*/
|
||||||
|
|
||||||
|
while (count > 0) {
|
||||||
|
len = min_t(unsigned int, count, sizeof(buffer));
|
||||||
|
|
||||||
|
/* Read some data from the byte channel. This function will
|
||||||
|
* never return more than EV_BYTE_CHANNEL_MAX_BYTES bytes.
|
||||||
|
*/
|
||||||
|
ev_byte_channel_receive(bc->handle, &len, buffer);
|
||||||
|
|
||||||
|
/* 'len' is now the amount of data that's been received. 'len'
|
||||||
|
* can't be zero, and most likely it's equal to one.
|
||||||
|
*/
|
||||||
|
|
||||||
|
/* Pass the received data to the tty layer. */
|
||||||
|
ret = tty_insert_flip_string(ttys, buffer, len);
|
||||||
|
|
||||||
|
/* 'ret' is the number of bytes that the TTY layer accepted.
|
||||||
|
* If it's not equal to 'len', then it means the buffer is
|
||||||
|
* full, which should never happen. If it does happen, we can
|
||||||
|
* exit gracefully, but we drop the last 'len - ret' characters
|
||||||
|
* that we read from the byte channel.
|
||||||
|
*/
|
||||||
|
if (ret != len)
|
||||||
|
break;
|
||||||
|
|
||||||
|
count -= len;
|
||||||
|
}
|
||||||
|
|
||||||
|
/* Tell the tty layer that we're done. */
|
||||||
|
tty_flip_buffer_push(ttys);
|
||||||
|
|
||||||
|
tty_kref_put(ttys);
|
||||||
|
|
||||||
|
return IRQ_HANDLED;
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* dequeue the transmit buffer to the hypervisor
|
||||||
|
*
|
||||||
|
* This function, which can be called in interrupt context, dequeues as much
|
||||||
|
* data as possible from the transmit buffer to the byte channel.
|
||||||
|
*/
|
||||||
|
static void ehv_bc_tx_dequeue(struct ehv_bc_data *bc)
|
||||||
|
{
|
||||||
|
unsigned int count;
|
||||||
|
unsigned int len, ret;
|
||||||
|
unsigned long flags;
|
||||||
|
|
||||||
|
do {
|
||||||
|
spin_lock_irqsave(&bc->lock, flags);
|
||||||
|
len = min_t(unsigned int,
|
||||||
|
CIRC_CNT_TO_END(bc->head, bc->tail, BUF_SIZE),
|
||||||
|
EV_BYTE_CHANNEL_MAX_BYTES);
|
||||||
|
|
||||||
|
ret = ev_byte_channel_send(bc->handle, &len, bc->buf + bc->tail);
|
||||||
|
|
||||||
|
/* 'len' is valid only if the return code is 0 or EV_EAGAIN */
|
||||||
|
if (!ret || (ret == EV_EAGAIN))
|
||||||
|
bc->tail = (bc->tail + len) & (BUF_SIZE - 1);
|
||||||
|
|
||||||
|
count = CIRC_CNT(bc->head, bc->tail, BUF_SIZE);
|
||||||
|
spin_unlock_irqrestore(&bc->lock, flags);
|
||||||
|
} while (count && !ret);
|
||||||
|
|
||||||
|
spin_lock_irqsave(&bc->lock, flags);
|
||||||
|
if (CIRC_CNT(bc->head, bc->tail, BUF_SIZE))
|
||||||
|
/*
|
||||||
|
* If we haven't emptied the buffer, then enable the TX IRQ.
|
||||||
|
* We'll get an interrupt when there's more room in the
|
||||||
|
* hypervisor's output buffer.
|
||||||
|
*/
|
||||||
|
enable_tx_interrupt(bc);
|
||||||
|
else
|
||||||
|
disable_tx_interrupt(bc);
|
||||||
|
spin_unlock_irqrestore(&bc->lock, flags);
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* byte channel transmit interupt handler
|
||||||
|
*
|
||||||
|
* This ISR is called whenever space becomes available for transmitting
|
||||||
|
* characters on a byte channel.
|
||||||
|
*/
|
||||||
|
static irqreturn_t ehv_bc_tty_tx_isr(int irq, void *data)
|
||||||
|
{
|
||||||
|
struct ehv_bc_data *bc = data;
|
||||||
|
struct tty_struct *ttys = tty_port_tty_get(&bc->port);
|
||||||
|
|
||||||
|
ehv_bc_tx_dequeue(bc);
|
||||||
|
if (ttys) {
|
||||||
|
tty_wakeup(ttys);
|
||||||
|
tty_kref_put(ttys);
|
||||||
|
}
|
||||||
|
|
||||||
|
return IRQ_HANDLED;
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* This function is called when the tty layer has data for us send. We store
|
||||||
|
* the data first in a circular buffer, and then dequeue as much of that data
|
||||||
|
* as possible.
|
||||||
|
*
|
||||||
|
* We don't need to worry about whether there is enough room in the buffer for
|
||||||
|
* all the data. The purpose of ehv_bc_tty_write_room() is to tell the tty
|
||||||
|
* layer how much data it can safely send to us. We guarantee that
|
||||||
|
* ehv_bc_tty_write_room() will never lie, so the tty layer will never send us
|
||||||
|
* too much data.
|
||||||
|
*/
|
||||||
|
static int ehv_bc_tty_write(struct tty_struct *ttys, const unsigned char *s,
|
||||||
|
int count)
|
||||||
|
{
|
||||||
|
struct ehv_bc_data *bc = ttys->driver_data;
|
||||||
|
unsigned long flags;
|
||||||
|
unsigned int len;
|
||||||
|
unsigned int written = 0;
|
||||||
|
|
||||||
|
while (1) {
|
||||||
|
spin_lock_irqsave(&bc->lock, flags);
|
||||||
|
len = CIRC_SPACE_TO_END(bc->head, bc->tail, BUF_SIZE);
|
||||||
|
if (count < len)
|
||||||
|
len = count;
|
||||||
|
if (len) {
|
||||||
|
memcpy(bc->buf + bc->head, s, len);
|
||||||
|
bc->head = (bc->head + len) & (BUF_SIZE - 1);
|
||||||
|
}
|
||||||
|
spin_unlock_irqrestore(&bc->lock, flags);
|
||||||
|
if (!len)
|
||||||
|
break;
|
||||||
|
|
||||||
|
s += len;
|
||||||
|
count -= len;
|
||||||
|
written += len;
|
||||||
|
}
|
||||||
|
|
||||||
|
ehv_bc_tx_dequeue(bc);
|
||||||
|
|
||||||
|
return written;
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* This function can be called multiple times for a given tty_struct, which is
|
||||||
|
* why we initialize bc->ttys in ehv_bc_tty_port_activate() instead.
|
||||||
|
*
|
||||||
|
* The tty layer will still call this function even if the device was not
|
||||||
|
* registered (i.e. tty_register_device() was not called). This happens
|
||||||
|
* because tty_register_device() is optional and some legacy drivers don't
|
||||||
|
* use it. So we need to check for that.
|
||||||
|
*/
|
||||||
|
static int ehv_bc_tty_open(struct tty_struct *ttys, struct file *filp)
|
||||||
|
{
|
||||||
|
struct ehv_bc_data *bc = &bcs[ttys->index];
|
||||||
|
|
||||||
|
if (!bc->dev)
|
||||||
|
return -ENODEV;
|
||||||
|
|
||||||
|
return tty_port_open(&bc->port, ttys, filp);
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* Amazingly, if ehv_bc_tty_open() returns an error code, the tty layer will
|
||||||
|
* still call this function to close the tty device. So we can't assume that
|
||||||
|
* the tty port has been initialized.
|
||||||
|
*/
|
||||||
|
static void ehv_bc_tty_close(struct tty_struct *ttys, struct file *filp)
|
||||||
|
{
|
||||||
|
struct ehv_bc_data *bc = &bcs[ttys->index];
|
||||||
|
|
||||||
|
if (bc->dev)
|
||||||
|
tty_port_close(&bc->port, ttys, filp);
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* Return the amount of space in the output buffer
|
||||||
|
*
|
||||||
|
* This is actually a contract between the driver and the tty layer outlining
|
||||||
|
* how much write room the driver can guarantee will be sent OR BUFFERED. This
|
||||||
|
* driver MUST honor the return value.
|
||||||
|
*/
|
||||||
|
static int ehv_bc_tty_write_room(struct tty_struct *ttys)
|
||||||
|
{
|
||||||
|
struct ehv_bc_data *bc = ttys->driver_data;
|
||||||
|
unsigned long flags;
|
||||||
|
int count;
|
||||||
|
|
||||||
|
spin_lock_irqsave(&bc->lock, flags);
|
||||||
|
count = CIRC_SPACE(bc->head, bc->tail, BUF_SIZE);
|
||||||
|
spin_unlock_irqrestore(&bc->lock, flags);
|
||||||
|
|
||||||
|
return count;
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* Stop sending data to the tty layer
|
||||||
|
*
|
||||||
|
* This function is called when the tty layer's input buffers are getting full,
|
||||||
|
* so the driver should stop sending it data. The easiest way to do this is to
|
||||||
|
* disable the RX IRQ, which will prevent ehv_bc_tty_rx_isr() from being
|
||||||
|
* called.
|
||||||
|
*
|
||||||
|
* The hypervisor will continue to queue up any incoming data. If there is any
|
||||||
|
* data in the queue when the RX interrupt is enabled, we'll immediately get an
|
||||||
|
* RX interrupt.
|
||||||
|
*/
|
||||||
|
static void ehv_bc_tty_throttle(struct tty_struct *ttys)
|
||||||
|
{
|
||||||
|
struct ehv_bc_data *bc = ttys->driver_data;
|
||||||
|
|
||||||
|
disable_irq(bc->rx_irq);
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* Resume sending data to the tty layer
|
||||||
|
*
|
||||||
|
* This function is called after previously calling ehv_bc_tty_throttle(). The
|
||||||
|
* tty layer's input buffers now have more room, so the driver can resume
|
||||||
|
* sending it data.
|
||||||
|
*/
|
||||||
|
static void ehv_bc_tty_unthrottle(struct tty_struct *ttys)
|
||||||
|
{
|
||||||
|
struct ehv_bc_data *bc = ttys->driver_data;
|
||||||
|
|
||||||
|
/* If there is any data in the queue when the RX interrupt is enabled,
|
||||||
|
* we'll immediately get an RX interrupt.
|
||||||
|
*/
|
||||||
|
enable_irq(bc->rx_irq);
|
||||||
|
}
|
||||||
|
|
||||||
|
static void ehv_bc_tty_hangup(struct tty_struct *ttys)
|
||||||
|
{
|
||||||
|
struct ehv_bc_data *bc = ttys->driver_data;
|
||||||
|
|
||||||
|
ehv_bc_tx_dequeue(bc);
|
||||||
|
tty_port_hangup(&bc->port);
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* TTY driver operations
|
||||||
|
*
|
||||||
|
* If we could ask the hypervisor how much data is still in the TX buffer, or
|
||||||
|
* at least how big the TX buffers are, then we could implement the
|
||||||
|
* .wait_until_sent and .chars_in_buffer functions.
|
||||||
|
*/
|
||||||
|
static const struct tty_operations ehv_bc_ops = {
|
||||||
|
.open = ehv_bc_tty_open,
|
||||||
|
.close = ehv_bc_tty_close,
|
||||||
|
.write = ehv_bc_tty_write,
|
||||||
|
.write_room = ehv_bc_tty_write_room,
|
||||||
|
.throttle = ehv_bc_tty_throttle,
|
||||||
|
.unthrottle = ehv_bc_tty_unthrottle,
|
||||||
|
.hangup = ehv_bc_tty_hangup,
|
||||||
|
};
|
||||||
|
|
||||||
|
/*
|
||||||
|
* initialize the TTY port
|
||||||
|
*
|
||||||
|
* This function will only be called once, no matter how many times
|
||||||
|
* ehv_bc_tty_open() is called. That's why we register the ISR here, and also
|
||||||
|
* why we initialize tty_struct-related variables here.
|
||||||
|
*/
|
||||||
|
static int ehv_bc_tty_port_activate(struct tty_port *port,
|
||||||
|
struct tty_struct *ttys)
|
||||||
|
{
|
||||||
|
struct ehv_bc_data *bc = container_of(port, struct ehv_bc_data, port);
|
||||||
|
int ret;
|
||||||
|
|
||||||
|
ttys->driver_data = bc;
|
||||||
|
|
||||||
|
ret = request_irq(bc->rx_irq, ehv_bc_tty_rx_isr, 0, "ehv-bc", bc);
|
||||||
|
if (ret < 0) {
|
||||||
|
dev_err(bc->dev, "could not request rx irq %u (ret=%i)\n",
|
||||||
|
bc->rx_irq, ret);
|
||||||
|
return ret;
|
||||||
|
}
|
||||||
|
|
||||||
|
/* request_irq also enables the IRQ */
|
||||||
|
bc->tx_irq_enabled = 1;
|
||||||
|
|
||||||
|
ret = request_irq(bc->tx_irq, ehv_bc_tty_tx_isr, 0, "ehv-bc", bc);
|
||||||
|
if (ret < 0) {
|
||||||
|
dev_err(bc->dev, "could not request tx irq %u (ret=%i)\n",
|
||||||
|
bc->tx_irq, ret);
|
||||||
|
free_irq(bc->rx_irq, bc);
|
||||||
|
return ret;
|
||||||
|
}
|
||||||
|
|
||||||
|
/* The TX IRQ is enabled only when we can't write all the data to the
|
||||||
|
* byte channel at once, so by default it's disabled.
|
||||||
|
*/
|
||||||
|
disable_tx_interrupt(bc);
|
||||||
|
|
||||||
|
return 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
static void ehv_bc_tty_port_shutdown(struct tty_port *port)
|
||||||
|
{
|
||||||
|
struct ehv_bc_data *bc = container_of(port, struct ehv_bc_data, port);
|
||||||
|
|
||||||
|
free_irq(bc->tx_irq, bc);
|
||||||
|
free_irq(bc->rx_irq, bc);
|
||||||
|
}
|
||||||
|
|
||||||
|
static const struct tty_port_operations ehv_bc_tty_port_ops = {
|
||||||
|
.activate = ehv_bc_tty_port_activate,
|
||||||
|
.shutdown = ehv_bc_tty_port_shutdown,
|
||||||
|
};
|
||||||
|
|
||||||
|
static int __devinit ehv_bc_tty_probe(struct platform_device *pdev)
|
||||||
|
{
|
||||||
|
struct device_node *np = pdev->dev.of_node;
|
||||||
|
struct ehv_bc_data *bc;
|
||||||
|
const uint32_t *iprop;
|
||||||
|
unsigned int handle;
|
||||||
|
int ret;
|
||||||
|
static unsigned int index = 1;
|
||||||
|
unsigned int i;
|
||||||
|
|
||||||
|
iprop = of_get_property(np, "hv-handle", NULL);
|
||||||
|
if (!iprop) {
|
||||||
|
dev_err(&pdev->dev, "no 'hv-handle' property in %s node\n",
|
||||||
|
np->name);
|
||||||
|
return -ENODEV;
|
||||||
|
}
|
||||||
|
|
||||||
|
/* We already told the console layer that the index for the console
|
||||||
|
* device is zero, so we need to make sure that we use that index when
|
||||||
|
* we probe the console byte channel node.
|
||||||
|
*/
|
||||||
|
handle = be32_to_cpu(*iprop);
|
||||||
|
i = (handle == stdout_bc) ? 0 : index++;
|
||||||
|
bc = &bcs[i];
|
||||||
|
|
||||||
|
bc->handle = handle;
|
||||||
|
bc->head = 0;
|
||||||
|
bc->tail = 0;
|
||||||
|
spin_lock_init(&bc->lock);
|
||||||
|
|
||||||
|
bc->rx_irq = irq_of_parse_and_map(np, 0);
|
||||||
|
bc->tx_irq = irq_of_parse_and_map(np, 1);
|
||||||
|
if ((bc->rx_irq == NO_IRQ) || (bc->tx_irq == NO_IRQ)) {
|
||||||
|
dev_err(&pdev->dev, "no 'interrupts' property in %s node\n",
|
||||||
|
np->name);
|
||||||
|
ret = -ENODEV;
|
||||||
|
goto error;
|
||||||
|
}
|
||||||
|
|
||||||
|
bc->dev = tty_register_device(ehv_bc_driver, i, &pdev->dev);
|
||||||
|
if (IS_ERR(bc->dev)) {
|
||||||
|
ret = PTR_ERR(bc->dev);
|
||||||
|
dev_err(&pdev->dev, "could not register tty (ret=%i)\n", ret);
|
||||||
|
goto error;
|
||||||
|
}
|
||||||
|
|
||||||
|
tty_port_init(&bc->port);
|
||||||
|
bc->port.ops = &ehv_bc_tty_port_ops;
|
||||||
|
|
||||||
|
dev_set_drvdata(&pdev->dev, bc);
|
||||||
|
|
||||||
|
dev_info(&pdev->dev, "registered /dev/%s%u for byte channel %u\n",
|
||||||
|
ehv_bc_driver->name, i, bc->handle);
|
||||||
|
|
||||||
|
return 0;
|
||||||
|
|
||||||
|
error:
|
||||||
|
irq_dispose_mapping(bc->tx_irq);
|
||||||
|
irq_dispose_mapping(bc->rx_irq);
|
||||||
|
|
||||||
|
memset(bc, 0, sizeof(struct ehv_bc_data));
|
||||||
|
return ret;
|
||||||
|
}
|
||||||
|
|
||||||
|
static int ehv_bc_tty_remove(struct platform_device *pdev)
|
||||||
|
{
|
||||||
|
struct ehv_bc_data *bc = dev_get_drvdata(&pdev->dev);
|
||||||
|
|
||||||
|
tty_unregister_device(ehv_bc_driver, bc - bcs);
|
||||||
|
|
||||||
|
irq_dispose_mapping(bc->tx_irq);
|
||||||
|
irq_dispose_mapping(bc->rx_irq);
|
||||||
|
|
||||||
|
return 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
static const struct of_device_id ehv_bc_tty_of_ids[] = {
|
||||||
|
{ .compatible = "epapr,hv-byte-channel" },
|
||||||
|
{}
|
||||||
|
};
|
||||||
|
|
||||||
|
static struct platform_driver ehv_bc_tty_driver = {
|
||||||
|
.driver = {
|
||||||
|
.owner = THIS_MODULE,
|
||||||
|
.name = "ehv-bc",
|
||||||
|
.of_match_table = ehv_bc_tty_of_ids,
|
||||||
|
},
|
||||||
|
.probe = ehv_bc_tty_probe,
|
||||||
|
.remove = ehv_bc_tty_remove,
|
||||||
|
};
|
||||||
|
|
||||||
|
/**
|
||||||
|
* ehv_bc_init - ePAPR hypervisor byte channel driver initialization
|
||||||
|
*
|
||||||
|
* This function is called when this module is loaded.
|
||||||
|
*/
|
||||||
|
static int __init ehv_bc_init(void)
|
||||||
|
{
|
||||||
|
struct device_node *np;
|
||||||
|
unsigned int count = 0; /* Number of elements in bcs[] */
|
||||||
|
int ret;
|
||||||
|
|
||||||
|
pr_info("ePAPR hypervisor byte channel driver\n");
|
||||||
|
|
||||||
|
/* Count the number of byte channels */
|
||||||
|
for_each_compatible_node(np, NULL, "epapr,hv-byte-channel")
|
||||||
|
count++;
|
||||||
|
|
||||||
|
if (!count)
|
||||||
|
return -ENODEV;
|
||||||
|
|
||||||
|
/* The array index of an element in bcs[] is the same as the tty index
|
||||||
|
* for that element. If you know the address of an element in the
|
||||||
|
* array, then you can use pointer math (e.g. "bc - bcs") to get its
|
||||||
|
* tty index.
|
||||||
|
*/
|
||||||
|
bcs = kzalloc(count * sizeof(struct ehv_bc_data), GFP_KERNEL);
|
||||||
|
if (!bcs)
|
||||||
|
return -ENOMEM;
|
||||||
|
|
||||||
|
ehv_bc_driver = alloc_tty_driver(count);
|
||||||
|
if (!ehv_bc_driver) {
|
||||||
|
ret = -ENOMEM;
|
||||||
|
goto error;
|
||||||
|
}
|
||||||
|
|
||||||
|
ehv_bc_driver->owner = THIS_MODULE;
|
||||||
|
ehv_bc_driver->driver_name = "ehv-bc";
|
||||||
|
ehv_bc_driver->name = ehv_bc_console.name;
|
||||||
|
ehv_bc_driver->type = TTY_DRIVER_TYPE_CONSOLE;
|
||||||
|
ehv_bc_driver->subtype = SYSTEM_TYPE_CONSOLE;
|
||||||
|
ehv_bc_driver->init_termios = tty_std_termios;
|
||||||
|
ehv_bc_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
|
||||||
|
tty_set_operations(ehv_bc_driver, &ehv_bc_ops);
|
||||||
|
|
||||||
|
ret = tty_register_driver(ehv_bc_driver);
|
||||||
|
if (ret) {
|
||||||
|
pr_err("ehv-bc: could not register tty driver (ret=%i)\n", ret);
|
||||||
|
goto error;
|
||||||
|
}
|
||||||
|
|
||||||
|
ret = platform_driver_register(&ehv_bc_tty_driver);
|
||||||
|
if (ret) {
|
||||||
|
pr_err("ehv-bc: could not register platform driver (ret=%i)\n",
|
||||||
|
ret);
|
||||||
|
goto error;
|
||||||
|
}
|
||||||
|
|
||||||
|
return 0;
|
||||||
|
|
||||||
|
error:
|
||||||
|
if (ehv_bc_driver) {
|
||||||
|
tty_unregister_driver(ehv_bc_driver);
|
||||||
|
put_tty_driver(ehv_bc_driver);
|
||||||
|
}
|
||||||
|
|
||||||
|
kfree(bcs);
|
||||||
|
|
||||||
|
return ret;
|
||||||
|
}
|
||||||
|
|
||||||
|
|
||||||
|
/**
|
||||||
|
* ehv_bc_exit - ePAPR hypervisor byte channel driver termination
|
||||||
|
*
|
||||||
|
* This function is called when this driver is unloaded.
|
||||||
|
*/
|
||||||
|
static void __exit ehv_bc_exit(void)
|
||||||
|
{
|
||||||
|
tty_unregister_driver(ehv_bc_driver);
|
||||||
|
put_tty_driver(ehv_bc_driver);
|
||||||
|
kfree(bcs);
|
||||||
|
}
|
||||||
|
|
||||||
|
module_init(ehv_bc_init);
|
||||||
|
module_exit(ehv_bc_exit);
|
||||||
|
|
||||||
|
MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
|
||||||
|
MODULE_DESCRIPTION("ePAPR hypervisor byte channel driver");
|
||||||
|
MODULE_LICENSE("GPL v2");
|
||||||
Reference in New Issue