linux-kernel - [PATCH V22 11/22] mmc: sdhci-uhs2: add reset function

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Message-Id: <20240913102836.6144-12-victorshihgli@gmail.com>
Date: Fri, 13 Sep 2024 18:28:25 +0800
From: Victor Shih <victorshihgli@...il.com>
To: ulf.hansson@...aro.org,
	adrian.hunter@...el.com
Cc: linux-mmc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	benchuanggli@...il.com,
	Lucas.Lai@...esyslogic.com.tw,
	HL.Liu@...esyslogic.com.tw,
	Greg.tu@...esyslogic.com.tw,
	dlunev@...omium.org,
	Victor Shih <victorshihgli@...il.com>,
	Ben Chuang <ben.chuang@...esyslogic.com.tw>,
	AKASHI Takahiro <takahiro.akashi@...aro.org>,
	Victor Shih <victor.shih@...esyslogic.com.tw>
Subject: [PATCH V22 11/22] mmc: sdhci-uhs2: add reset function

From: Victor Shih <victor.shih@...esyslogic.com.tw>

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>
Signed-off-by: Victor Shih <victor.shih@...esyslogic.com.tw>
---

Updates in V17:
 - Move the sdhci_uhs2_reset_cmd_data() to the other patch it was used
   for the first time.

Updates in V16:
 - Add sdhci_uhs2_reset_cmd_data() function.

Updates in V15:
 - Refer the SD Host Controller Standard Specification Section 3.10
   to add reset command data mechanism.

Updates in V14:
 - Since mmc_card_uhs2() is the same as sdhci_uhs2_mode(), so drop
   sdhci_uhs2_mode() and use mmc_card_uhs2() instead of sdhci_uhs2_mode().

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 | 37 +++++++++++++++++++++++++++++++++++
 drivers/mmc/host/sdhci-uhs2.h |  1 +
 2 files changed, 38 insertions(+)

diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
index 14514710e763..71c60952a40a 100644
--- a/drivers/mmc/host/sdhci-uhs2.c
+++ b/drivers/mmc/host/sdhci-uhs2.c
@@ -10,7 +10,9 @@
  *  Author: AKASHI Takahiro <takahiro.akashi@...aro.org>
  */
 
+#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 (!(mmc_card_uhs2(host->mmc)))
@@ -49,6 +53,39 @@ 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)
+{
+	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..caaf9fba4975 100644
--- a/drivers/mmc/host/sdhci-uhs2.h
+++ b/drivers/mmc/host/sdhci-uhs2.h
@@ -177,5 +177,6 @@
 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 */
-- 
2.25.1