linux-kernel - [RFC PATCH v3.2 12/29] mmc: sdhci-uhs2: add reset function

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Date:   Thu, 22 Jul 2021 12:01:07 +0800
From:   Jason Lai <jasonlai.genesyslogic@...il.com>
To:     ulf.hansson@...aro.org, adrian.hunter@...el.com
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        ben.chuang@...esyslogic.com.tw, greg.tu@...esyslogic.com.tw,
        jason.lai@...esyslogiv.com.tw,
        AKASHI Takahiro <takahiro.akashi@...aro.org>
Subject: [RFC PATCH v3.2 12/29] mmc: sdhci-uhs2: add reset function

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

Signed-off-by: Ben Chuang <ben.chuang@...esyslogic.com.tw>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
---
 drivers/mmc/host/sdhci-uhs2.c | 49 +++++++++++++++++++++++++++++++++++
 drivers/mmc/host/sdhci-uhs2.h |  1 +
 drivers/mmc/host/sdhci.c      |  3 ++-
 drivers/mmc/host/sdhci.h      |  1 +
 4 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
index 08905ed081fb..e2b9743fe17d 100644
--- a/drivers/mmc/host/sdhci-uhs2.c
+++ b/drivers/mmc/host/sdhci-uhs2.c
@@ -10,6 +10,7 @@
  *  Author: AKASHI Takahiro <takahiro.akashi@...aro.org>
  */

+#include <linux/delay.h>
 #include <linux/module.h>

 #include "sdhci.h"
@@ -49,6 +50,54 @@ void sdhci_uhs2_dump_regs(struct sdhci_host *host)
 }
 EXPORT_SYMBOL_GPL(sdhci_uhs2_dump_regs);

+/*****************************************************************************\
+ *                                                                           *
+ * Low level functions                                                       *
+ *                                                                           *
+\*****************************************************************************/
+
+/**
+ * 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)
+{
+	unsigned long timeout;
+
+	if (!(host->mmc->caps & MMC_CAP_UHS2))
+		return;
+
+	sdhci_writew(host, mask, SDHCI_UHS2_SW_RESET);
+
+	if (mask & SDHCI_UHS2_SW_RESET_FULL) {
+		host->clock = 0;
+		/* Reset-all turns off SD Bus Power */
+		if (host->quirks2 & SDHCI_QUIRK2_CARD_ON_NEEDS_BUS_ON)
+			sdhci_runtime_pm_bus_off(host);
+	}
+
+	/* Wait max 100 ms */
+	timeout = 10000;
+
+	/* hw clears the bit when it's done */
+	while (sdhci_readw(host, SDHCI_UHS2_SW_RESET) & mask) {
+		if (timeout == 0) {
+			pr_err("%s: %s: Reset 0x%x never completed.\n",
+			       __func__, mmc_hostname(host->mmc), (int)mask);
+			pr_err("%s: clean reset bit\n",
+			       mmc_hostname(host->mmc));
+			sdhci_writeb(host, 0, SDHCI_UHS2_SW_RESET);
+			return;
+		}
+		timeout--;
+		udelay(10);
+	}
+}
+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 b9529d32b58d..7bb7a0d67109 100644
--- a/drivers/mmc/host/sdhci-uhs2.h
+++ b/drivers/mmc/host/sdhci-uhs2.h
@@ -210,5 +210,6 @@
 struct sdhci_host;

 void sdhci_uhs2_dump_regs(struct sdhci_host *host);
+void sdhci_uhs2_reset(struct sdhci_host *host, u16 mask);

 #endif /* __SDHCI_UHS2_H */
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 97e7e04e4614..78db850dc1f3 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -194,13 +194,14 @@ static void sdhci_runtime_pm_bus_on(struct sdhci_host *host)
 	pm_runtime_get_noresume(mmc_dev(host->mmc));
 }

-static void sdhci_runtime_pm_bus_off(struct sdhci_host *host)
+void sdhci_runtime_pm_bus_off(struct sdhci_host *host)
 {
 	if (!host->bus_on)
 		return;
 	host->bus_on = false;
 	pm_runtime_put_noidle(mmc_dev(host->mmc));
 }
+EXPORT_SYMBOL_GPL(sdhci_runtime_pm_bus_off);

 void sdhci_reset(struct sdhci_host *host, u8 mask)
 {
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index d9d7a76cedc1..b9932423db08 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -831,6 +831,7 @@ static inline void sdhci_read_caps(struct sdhci_host *host)
 	__sdhci_read_caps(host, NULL, NULL, NULL);
 }

+void sdhci_runtime_pm_bus_off(struct sdhci_host *host);
 u16 sdhci_calc_clk(struct sdhci_host *host, unsigned int clock,
 		   unsigned int *actual_clock);
 void sdhci_set_clock(struct sdhci_host *host, unsigned int clock);
--
2.32.0