mmc: sdhci-iproc: fix 32bit writes for TRANSFER_MODE register

When the host controller accepts only 32bit writes, the value of the
16bit TRANSFER_MODE register, that has the same 32bit address as the
16bit COMMAND register, needs to be saved and it will be written
in a 32bit write together with the command as this will trigger the
host to send the command on the SD interface.
When sending the tuning command, TRANSFER_MODE is written and then
sdhci_set_transfer_mode reads it back to clear AUTO_CMD12 bit and
write it again resulting in wrong value to be written because the
initial write value was saved in a shadow and the read-back returned
a wrong value, from the register.
Fix sdhci_iproc_readw to return the saved value of TRANSFER_MODE
when a saved value exist.
Same fix for read of BLOCK_SIZE and BLOCK_COUNT registers, that are
saved for a different reason, although a scenario that will cause the
mentioned problem on this registers is not probable.

Fixes: b580c52d58d9 ("mmc: sdhci-iproc: add IPROC SDHCI driver")
Signed-off-by: Corneliu Doban <corneliu.doban@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Cc: stable@vger.kernel.org # v4.1+
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/sdhci-iproc.c b/drivers/mmc/host/sdhci-iproc.c
index 6f430da9ae2f5f87228cfbed0237425ea0e16b2a..1f0ab08e8adfe1ee134cb36144fb15e28b1222b0 100644 (file)
--- a/drivers/mmc/host/sdhci-iproc.c
+++ b/drivers/mmc/host/sdhci-iproc.c
@@ -33,6 +33,8 @@ struct sdhci_iproc_host {
        const struct sdhci_iproc_data *data;
        u32 shadow_cmd;
        u32 shadow_blk;
+       bool is_cmd_shadowed;
+       bool is_blk_shadowed;
 };
 
 #define REG_OFFSET_IN_BITS(reg) ((reg) << 3 & 0x18)
@@ -48,8 +50,22 @@ static inline u32 sdhci_iproc_readl(struct sdhci_host *host, int reg)
 
 static u16 sdhci_iproc_readw(struct sdhci_host *host, int reg)
 {
-       u32 val = sdhci_iproc_readl(host, (reg & ~3));
-       u16 word = val >> REG_OFFSET_IN_BITS(reg) & 0xffff;
+       struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+       struct sdhci_iproc_host *iproc_host = sdhci_pltfm_priv(pltfm_host);
+       u32 val;
+       u16 word;
+
+       if ((reg == SDHCI_TRANSFER_MODE) && iproc_host->is_cmd_shadowed) {
+               /* Get the saved transfer mode */
+               val = iproc_host->shadow_cmd;
+       } else if ((reg == SDHCI_BLOCK_SIZE || reg == SDHCI_BLOCK_COUNT) &&
+                  iproc_host->is_blk_shadowed) {
+               /* Get the saved block info */
+               val = iproc_host->shadow_blk;
+       } else {
+               val = sdhci_iproc_readl(host, (reg & ~3));
+       }
+       word = val >> REG_OFFSET_IN_BITS(reg) & 0xffff;
        return word;
 }
 
@@ -105,13 +121,15 @@ static void sdhci_iproc_writew(struct sdhci_host *host, u16 val, int reg)
 
        if (reg == SDHCI_COMMAND) {
                /* Write the block now as we are issuing a command */
-               if (iproc_host->shadow_blk != 0) {
+               if (iproc_host->is_blk_shadowed) {
                        sdhci_iproc_writel(host, iproc_host->shadow_blk,
                                SDHCI_BLOCK_SIZE);
-                       iproc_host->shadow_blk = 0;
+                       iproc_host->is_blk_shadowed = false;
                }
                oldval = iproc_host->shadow_cmd;
-       } else if (reg == SDHCI_BLOCK_SIZE || reg == SDHCI_BLOCK_COUNT) {
+               iproc_host->is_cmd_shadowed = false;
+       } else if ((reg == SDHCI_BLOCK_SIZE || reg == SDHCI_BLOCK_COUNT) &&
+                  iproc_host->is_blk_shadowed) {
                /* Block size and count are stored in shadow reg */
                oldval = iproc_host->shadow_blk;
        } else {
@@ -123,9 +141,11 @@ static void sdhci_iproc_writew(struct sdhci_host *host, u16 val, int reg)
        if (reg == SDHCI_TRANSFER_MODE) {
                /* Save the transfer mode until the command is issued */
                iproc_host->shadow_cmd = newval;
+               iproc_host->is_cmd_shadowed = true;
        } else if (reg == SDHCI_BLOCK_SIZE || reg == SDHCI_BLOCK_COUNT) {
                /* Save the block info until the command is issued */
                iproc_host->shadow_blk = newval;
+               iproc_host->is_blk_shadowed = true;
        } else {
                /* Command or other regular 32-bit write */
                sdhci_iproc_writel(host, newval, reg & ~3);