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>

1 files changed, 29 insertions, 1 deletions

diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
index 571cd80521c7..18d3f19ef4e5 100644
--- a/drivers/mmc/host/omap_hsmmc.c
+++ b/drivers/mmc/host/omap_hsmmc.c
@@ -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