[PATCH V13 11/21] mmc: sdhci-uhs2: add reset function and uhs2_mode function

[Victor Shih <victorshihgli@xxxxxxxxx>]

From: Victor Shih <victor.shih@xxxxxxxxxxxxxxxxxxx>

Sdhci_uhs2_reset() does a UHS-II specific reset operation.

Signed-off-by: Ben Chuang <ben.chuang@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
Signed-off-by: Victor Shih <victor.shih@xxxxxxxxxxxxxxxxxxx>
---

Updates in V13:
 - Use ios timing to stead MMC_UHS2_SUPPORT for indicate the UHS2 mode.

Updates in V8:
 - Adjust the position of matching brackets.

Updates in V6:
 - Remove unnecessary functions and simplify code.

---

 drivers/mmc/host/sdhci-uhs2.c | 45 +++++++++++++++++++++++++++++++++++
 drivers/mmc/host/sdhci-uhs2.h |  2 ++
 2 files changed, 47 insertions(+)

diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
index e339821d3504..ef6f02583d61 100644
--- a/drivers/mmc/host/sdhci-uhs2.c
+++ b/drivers/mmc/host/sdhci-uhs2.c
@@ -10,7 +10,9 @@
  *  Author: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
  */
 
+#include <linux/delay.h>
 #include <linux/module.h>
+#include <linux/iopoll.h>
 
 #include "sdhci.h"
 #include "sdhci-uhs2.h"
@@ -21,6 +23,8 @@
 #define SDHCI_UHS2_DUMP(f, x...) \
 	pr_err("%s: " DRIVER_NAME ": " f, mmc_hostname(host->mmc), ## x)
 
+#define UHS2_RESET_TIMEOUT_100MS		100000
+
 void sdhci_uhs2_dump_regs(struct sdhci_host *host)
 {
 	if (!(sdhci_uhs2_mode(host)))
@@ -49,6 +53,47 @@ void sdhci_uhs2_dump_regs(struct sdhci_host *host)
 }
 EXPORT_SYMBOL_GPL(sdhci_uhs2_dump_regs);
 
+/*****************************************************************************\
+ *                                                                           *
+ * Low level functions                                                       *
+ *                                                                           *
+\*****************************************************************************/
+
+bool sdhci_uhs2_mode(struct sdhci_host *host)
+{
+	return	host->mmc->ios.timing == MMC_TIMING_UHS2_SPEED_A ||
+		host->mmc->ios.timing == MMC_TIMING_UHS2_SPEED_B ||
+		host->mmc->ios.timing == MMC_TIMING_UHS2_SPEED_A_HD ||
+		host->mmc->ios.timing == MMC_TIMING_UHS2_SPEED_B_HD;
+}
+
+/**
+ * sdhci_uhs2_reset - invoke SW reset
+ * @host: SDHCI host
+ * @mask: Control mask
+ *
+ * Invoke SW reset, depending on a bit in @mask and wait for completion.
+ */
+void sdhci_uhs2_reset(struct sdhci_host *host, u16 mask)
+{
+	u32 val;
+
+	sdhci_writew(host, mask, SDHCI_UHS2_SW_RESET);
+
+	if (mask & SDHCI_UHS2_SW_RESET_FULL)
+		host->clock = 0;
+
+	/* hw clears the bit when it's done */
+	if (read_poll_timeout_atomic(sdhci_readw, val, !(val & mask), 10,
+				     UHS2_RESET_TIMEOUT_100MS, true, host, SDHCI_UHS2_SW_RESET)) {
+		pr_warn("%s: %s: Reset 0x%x never completed. %s: clean reset bit.\n", __func__,
+			mmc_hostname(host->mmc), (int)mask, mmc_hostname(host->mmc));
+		sdhci_writeb(host, 0, SDHCI_UHS2_SW_RESET);
+		return;
+	}
+}
+EXPORT_SYMBOL_GPL(sdhci_uhs2_reset);
+
 /*****************************************************************************\
  *                                                                           *
  * Driver init/exit                                                          *
diff --git a/drivers/mmc/host/sdhci-uhs2.h b/drivers/mmc/host/sdhci-uhs2.h
index 2bfe18d29bca..8253d50f7852 100644
--- a/drivers/mmc/host/sdhci-uhs2.h
+++ b/drivers/mmc/host/sdhci-uhs2.h
@@ -177,5 +177,7 @@
 struct sdhci_host;
 
 void sdhci_uhs2_dump_regs(struct sdhci_host *host);
+bool sdhci_uhs2_mode(struct sdhci_host *host);
+void sdhci_uhs2_reset(struct sdhci_host *host, u16 mask);
 
 #endif /* __SDHCI_UHS2_H */
-- 
2.25.1