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mmc: omap_hsmmc: Enable HSPE bit for high speed cards 

HSMMC IP on AM33xx need a special setting to handle High-speed cards.
Other platforms like TI81xx, OMAP4 may need this as-well. This depends
on the HSMMC IP timing closure done for the high speed cards.

From AM335x TRM (SPRUH73F - 18.3.12 Output Signals Generation):

The MMC/SD/SDIO output signals can be driven on either falling edge or
rising edge depending on the SD_HCTL[2] HSPE bit. This feature allows
to reach better timing performance, and thus to increase data transfer
frequency.

There are few pre-requisites for enabling the HSPE bit
- Controller should support High-Speed-Enable Bit and
- Controller should not be using DDR Mode and
- Controller should advertise that it supports High Speed in
  capabilities register and
- MMC/SD clock coming out of controller > 25MHz

Signed-off-by: Hebbar, Gururaja <gururaja.hebbar@ti.com>
Signed-off-by: Venkatraman S <svenkatr@ti.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
Hebbar, Gururaja 2012-11-19 21:59:58 +05:30 committed by Chris Ball
parent dc7745bd32
commit cd587096c0
3 changed files with 31 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt
View File

@ -19,6 +19,7 @@ ti,dual-volt: boolean, supports dual voltage cards
"supply-name" examples are "vmmc", "vmmc_aux" etc
ti,non-removable: non-removable slot (like eMMC)
ti,needs-special-reset: Requires a special softreset sequence
ti,needs-special-hs-handling: HSMMC IP needs special setting for handling High Speed
Example:
mmc1: mmc@0x4809c000 {

1
arch/arm/plat-omap/include/plat/mmc.h
View File

@ -126,6 +126,7 @@ struct omap_mmc_platform_data {
/* we can put the features above into this variable */
#define HSMMC_HAS_PBIAS (1 << 0)
#define HSMMC_HAS_UPDATED_RESET (1 << 1)
#define HSMMC_HAS_HSPE_SUPPORT (1 << 2)
unsigned features;
int switch_pin; /* gpio (card detect) */

30
drivers/mmc/host/omap_hsmmc.c
View File

@ -63,6 +63,7 @@
#define VS18 (1 << 26)
#define VS30 (1 << 25)
#define HSS (1 << 21)
#define SDVS18 (0x5 << 9)
#define SDVS30 (0x6 << 9)
#define SDVS33 (0x7 << 9)
@ -90,6 +91,7 @@
#define MSBS (1 << 5)
#define BCE (1 << 1)
#define FOUR_BIT (1 << 1)
#define HSPE (1 << 2)
#define DDR (1 << 19)
#define DW8 (1 << 5)
#define CC 0x1
@ -495,6 +497,7 @@ static void omap_hsmmc_set_clock(struct omap_hsmmc_host *host)
struct mmc_ios *ios = &host->mmc->ios;
unsigned long regval;
unsigned long timeout;
unsigned long clkdiv;
dev_vdbg(mmc_dev(host->mmc), "Set clock to %uHz\n", ios->clock);
@ -502,7 +505,8 @@ static void omap_hsmmc_set_clock(struct omap_hsmmc_host *host)
regval = OMAP_HSMMC_READ(host->base, SYSCTL);
regval = regval & ~(CLKD_MASK | DTO_MASK);
regval = regval | (calc_divisor(host, ios) << 6) | (DTO << 16);
clkdiv = calc_divisor(host, ios);
regval = regval | (clkdiv << 6) | (DTO << 16);
OMAP_HSMMC_WRITE(host->base, SYSCTL, regval);
OMAP_HSMMC_WRITE(host->base, SYSCTL,
OMAP_HSMMC_READ(host->base, SYSCTL) | ICE);
@ -513,6 +517,27 @@ static void omap_hsmmc_set_clock(struct omap_hsmmc_host *host)
&& time_before(jiffies, timeout))
cpu_relax();
/*
* Enable High-Speed Support
* Pre-Requisites
* - Controller should support High-Speed-Enable Bit
* - Controller should not be using DDR Mode
* - Controller should advertise that it supports High Speed
* in capabilities register
* - MMC/SD clock coming out of controller > 25MHz
*/
if ((mmc_slot(host).features & HSMMC_HAS_HSPE_SUPPORT) &&
(ios->timing != MMC_TIMING_UHS_DDR50) &&
((OMAP_HSMMC_READ(host->base, CAPA) & HSS) == HSS)) {
regval = OMAP_HSMMC_READ(host->base, HCTL);
if (clkdiv && (clk_get_rate(host->fclk)/clkdiv) > 25000000)
regval |= HSPE;
else
regval &= ~HSPE;
OMAP_HSMMC_WRITE(host->base, HCTL, regval);
}
omap_hsmmc_start_clock(host);
}
@ -1715,6 +1740,9 @@ static struct omap_mmc_platform_data *of_get_hsmmc_pdata(struct device *dev)
if (!of_property_read_u32(np, "max-frequency", &max_freq))
pdata->max_freq = max_freq;
if (of_find_property(np, "ti,needs-special-hs-handling", NULL))
pdata->slots[0].features |= HSMMC_HAS_HSPE_SUPPORT;
return pdata;
}
#else