linux-kernel - [RFC PATCH v3.1 15/27] mmc: sdhci-uhs2: add set

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Message-Id: <20201106022726.19831-16-takahiro.akashi@linaro.org>
Date:   Fri,  6 Nov 2020 11:27:14 +0900
From:   AKASHI Takahiro <takahiro.akashi@...aro.org>
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,
        AKASHI Takahiro <takahiro.akashi@...aro.org>
Subject: [RFC PATCH v3.1 15/27] mmc: sdhci-uhs2: add set_timeout()

This is a UHS-II version of sdhci's set_timeout() 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 | 85 +++++++++++++++++++++++++++++++++++
 drivers/mmc/host/sdhci-uhs2.h |  1 +
 2 files changed, 86 insertions(+)

diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
index 1eca89359351..d9e98c097bfe 100644
--- a/drivers/mmc/host/sdhci-uhs2.c
+++ b/drivers/mmc/host/sdhci-uhs2.c
@@ -178,6 +178,91 @@ void sdhci_uhs2_set_power(struct sdhci_host *host, unsigned char mode,
 }
 EXPORT_SYMBOL_GPL(sdhci_uhs2_set_power);
 
+static u8 sdhci_calc_timeout_uhs2(struct sdhci_host *host, u8 *cmd_res,
+				  u8 *dead_lock)
+{
+	u8 count;
+	unsigned int cmd_res_timeout, dead_lock_timeout, current_timeout;
+
+	/*
+	 * If the host controller provides us with an incorrect timeout
+	 * value, just skip the check and use 0xE.  The hardware may take
+	 * longer to time out, but that's much better than having a too-short
+	 * timeout value.
+	 */
+	if (host->quirks & SDHCI_QUIRK_BROKEN_TIMEOUT_VAL) {
+		*cmd_res = 0xE;
+		*dead_lock = 0xE;
+		return 0xE;
+	}
+
+	/* timeout in us */
+	cmd_res_timeout = 5 * 1000;
+	dead_lock_timeout = 1 * 1000 * 1000;
+
+	/*
+	 * Figure out needed cycles.
+	 * We do this in steps in order to fit inside a 32 bit int.
+	 * The first step is the minimum timeout, which will have a
+	 * minimum resolution of 6 bits:
+	 * (1) 2^13*1000 > 2^22,
+	 * (2) host->timeout_clk < 2^16
+	 *     =>
+	 *     (1) / (2) > 2^6
+	 */
+	count = 0;
+	current_timeout = (1 << 13) * 1000 / host->timeout_clk;
+	while (current_timeout < cmd_res_timeout) {
+		count++;
+		current_timeout <<= 1;
+		if (count >= 0xF)
+			break;
+	}
+
+	if (count >= 0xF) {
+		DBG("%s: Too large timeout 0x%x requested for CMD_RES!\n",
+		    mmc_hostname(host->mmc), count);
+		count = 0xE;
+	}
+	*cmd_res = count;
+
+	count = 0;
+	current_timeout = (1 << 13) * 1000 / host->timeout_clk;
+	while (current_timeout < dead_lock_timeout) {
+		count++;
+		current_timeout <<= 1;
+		if (count >= 0xF)
+			break;
+	}
+
+	if (count >= 0xF) {
+		DBG("%s: Too large timeout 0x%x requested for DEADLOCK!\n",
+		    mmc_hostname(host->mmc), count);
+		count = 0xE;
+	}
+	*dead_lock = count;
+
+	return count;
+}
+
+static void __sdhci_uhs2_set_timeout(struct sdhci_host *host)
+{
+	u8 cmd_res, dead_lock;
+
+	sdhci_calc_timeout_uhs2(host, &cmd_res, &dead_lock);
+	cmd_res |= dead_lock << SDHCI_UHS2_TIMER_CTRL_DEADLOCK_SHIFT;
+	sdhci_writeb(host, cmd_res, SDHCI_UHS2_TIMER_CTRL);
+}
+
+void sdhci_uhs2_set_timeout(struct sdhci_host *host, struct mmc_command *cmd)
+{
+	__sdhci_set_timeout(host, cmd);
+
+	if (host->mmc->flags & MMC_UHS2_SUPPORT)
+		__sdhci_uhs2_set_timeout(host);
+}
+EXPORT_SYMBOL_GPL(sdhci_uhs2_set_timeout);
+
 /*****************************************************************************\
  *                                                                           *
  * MMC callbacks                                                             *
diff --git a/drivers/mmc/host/sdhci-uhs2.h b/drivers/mmc/host/sdhci-uhs2.h
index 3c19d8e44c36..efe70577bc74 100644
--- a/drivers/mmc/host/sdhci-uhs2.h
+++ b/drivers/mmc/host/sdhci-uhs2.h
@@ -213,5 +213,6 @@ void sdhci_uhs2_dump_regs(struct sdhci_host *host);
 void sdhci_uhs2_reset(struct sdhci_host *host, u16 mask);
 void sdhci_uhs2_set_power(struct sdhci_host *host, unsigned char mode,
 			  unsigned short vdd);
+void sdhci_uhs2_set_timeout(struct sdhci_host *host, struct mmc_command *cmd);
 
 #endif /* __SDHCI_UHS2_H */
-- 
2.28.0