Add a verify option to driver to print out an error message if a
potential back to back write could cause a clock domain issue.
Signed-off-by: Scott Branden <sbranden@xxxxxxxxxxxx>
---
drivers/mmc/host/Kconfig | 9 +++++++++
drivers/mmc/host/sdhci-bcm2835.c | 17 +++++++++++++++++
2 files changed, 26 insertions(+)
diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
index 1386065..020de98 100644
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -292,6 +292,15 @@ config MMC_SDHCI_BCM2835
If unsure, say N.
+config MMC_SDHCI_BCM2835_VERIFY_WORKAROUND
+ bool "Verify BCM2835 workaround does not do back to back writes"
+ depends on MMC_SDHCI_BCM2835
+ default y
+ help
+ This enables code that verifies the bcm2835 workaround.
+ The verification code checks that back to back writes to the same
+ register do not occur.
+
config MMC_MOXART
tristate "MOXART SD/MMC Host Controller support"
depends on ARCH_MOXART && MMC
diff --git a/drivers/mmc/host/sdhci-bcm2835.c b/drivers/mmc/host/sdhci-bcm2835.c
index f8c450a..11af27f 100644
--- a/drivers/mmc/host/sdhci-bcm2835.c
+++ b/drivers/mmc/host/sdhci-bcm2835.c
@@ -27,6 +27,9 @@
struct bcm2835_sdhci_host {
u32 shadow_cmd;
u32 shadow_blk;
+#ifdef CONFIG_MMC_SDHCI_BCM2835_VERIFY_WORKAROUND
+ int previous_reg;
+#endif
};
#define REG_OFFSET_IN_BITS(reg) ((reg) << 3 & 0x18)
@@ -58,6 +61,20 @@ static u8 bcm2835_sdhci_readb(struct sdhci_host *host, int reg)
static inline void bcm2835_sdhci_writel(struct sdhci_host *host,
u32 val, int reg)
{
+#ifdef CONFIG_MMC_SDHCI_BCM2835_VERIFY_WORKAROUND
+ struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+ struct bcm2835_sdhci_host *bcm2835_host = pltfm_host->priv;
+
+ if (bcm2835_host->previous_reg == reg) {
+ if ((reg != SDHCI_HOST_CONTROL)
+ && (reg != SDHCI_CLOCK_CONTROL)) {
+ dev_err(mmc_dev(host->mmc),
+ "back-to-back write to 0x%x\n", reg);
+ }
+ }
+ bcm2835_host->previous_reg = reg;
+#endif
+
writel(val, host->ioaddr + reg);
}
--
1.7.9.5
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