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Date:   Wed, 26 Aug 2020 20:50:01 -0700
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     <adrian.hunter@...el.com>, <ulf.hansson@...aro.org>,
        <thierry.reding@...il.com>, <jonathanh@...dia.com>,
        <robh+dt@...nel.org>
CC:     <skomatineni@...dia.com>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-mmc@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <stable@...r.kernel.org>
Subject: [PATCH v6 7/7] sdhci: tegra: Add missing TMCLK for data timeout

commit b5a84ecf025a ("mmc: tegra: Add Tegra210 support")

Tegra210 and later has a separate sdmmc_legacy_tm (TMCLK) used by Tegra
SDMMC hawdware for data timeout to achive better timeout than using
SDCLK and using TMCLK is recommended.

USE_TMCLK_FOR_DATA_TIMEOUT bit in Tegra SDMMC register
SDHCI_TEGRA_VENDOR_SYS_SW_CTRL can be used to choose either TMCLK or
SDCLK for data timeout.

Default USE_TMCLK_FOR_DATA_TIMEOUT bit is set to 1 and TMCLK is used
for data timeout by Tegra SDMMC hardware and having TMCLK not enabled
is not recommended.

So, this patch adds quirk NVQUIRK_HAS_TMCLK for SoC having separate
timeout clock and keeps TMCLK enabled all the time.

Fixes: b5a84ecf025a ("mmc: tegra: Add Tegra210 support")
Cc: stable <stable@...r.kernel.org> # 5.4
Tested-by: Jon Hunter <jonathanh@...dia.com>
Reviewed-by: Jon Hunter <jonathanh@...dia.com>
Acked-by: Adrian Hunter <adrian.hunter@...el.com>
Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
---
 drivers/mmc/host/sdhci-tegra.c | 90 ++++++++++++++++++++++++++++++++++++++----
 1 file changed, 82 insertions(+), 8 deletions(-)

diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
index 31ed321..f69ca8d 100644
--- a/drivers/mmc/host/sdhci-tegra.c
+++ b/drivers/mmc/host/sdhci-tegra.c
@@ -13,6 +13,7 @@
 #include <linux/clk.h>
 #include <linux/io.h>
 #include <linux/of.h>
+#include <linux/of_clk.h>
 #include <linux/of_device.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/regulator/consumer.h>
@@ -110,6 +111,12 @@
 #define NVQUIRK_DIS_CARD_CLK_CONFIG_TAP			BIT(8)
 #define NVQUIRK_CQHCI_DCMD_R1B_CMD_TIMING		BIT(9)
 
+/*
+ * NVQUIRK_HAS_TMCLK is for SoC's having separate timeout clock for Tegra
+ * SDMMC hardware data timeout.
+ */
+#define NVQUIRK_HAS_TMCLK				BIT(10)
+
 /* SDMMC CQE Base Address for Tegra Host Ver 4.1 and Higher */
 #define SDHCI_TEGRA_CQE_BASE_ADDR			0xF000
 
@@ -140,6 +147,7 @@ struct sdhci_tegra_autocal_offsets {
 struct sdhci_tegra {
 	const struct sdhci_tegra_soc_data *soc_data;
 	struct gpio_desc *power_gpio;
+	struct clk *tmclk;
 	bool ddr_signaling;
 	bool pad_calib_required;
 	bool pad_control_available;
@@ -1433,7 +1441,8 @@ static const struct sdhci_tegra_soc_data soc_data_tegra210 = {
 		    NVQUIRK_HAS_PADCALIB |
 		    NVQUIRK_DIS_CARD_CLK_CONFIG_TAP |
 		    NVQUIRK_ENABLE_SDR50 |
-		    NVQUIRK_ENABLE_SDR104,
+		    NVQUIRK_ENABLE_SDR104 |
+		    NVQUIRK_HAS_TMCLK,
 	.min_tap_delay = 106,
 	.max_tap_delay = 185,
 };
@@ -1471,6 +1480,7 @@ static const struct sdhci_tegra_soc_data soc_data_tegra186 = {
 		    NVQUIRK_DIS_CARD_CLK_CONFIG_TAP |
 		    NVQUIRK_ENABLE_SDR50 |
 		    NVQUIRK_ENABLE_SDR104 |
+		    NVQUIRK_HAS_TMCLK |
 		    NVQUIRK_CQHCI_DCMD_R1B_CMD_TIMING,
 	.min_tap_delay = 84,
 	.max_tap_delay = 136,
@@ -1483,7 +1493,8 @@ static const struct sdhci_tegra_soc_data soc_data_tegra194 = {
 		    NVQUIRK_HAS_PADCALIB |
 		    NVQUIRK_DIS_CARD_CLK_CONFIG_TAP |
 		    NVQUIRK_ENABLE_SDR50 |
-		    NVQUIRK_ENABLE_SDR104,
+		    NVQUIRK_ENABLE_SDR104 |
+		    NVQUIRK_HAS_TMCLK,
 	.min_tap_delay = 96,
 	.max_tap_delay = 139,
 };
@@ -1611,15 +1622,76 @@ static int sdhci_tegra_probe(struct platform_device *pdev)
 		goto err_power_req;
 	}
 
-	clk = devm_clk_get(mmc_dev(host->mmc), NULL);
-	if (IS_ERR(clk)) {
-		rc = PTR_ERR(clk);
+	/*
+	 * Tegra210 and later has separate SDMMC_LEGACY_TM clock used for
+	 * hardware data timeout clock and SW can choose TMCLK or SDCLK for
+	 * hardware data timeout through the bit USE_TMCLK_FOR_DATA_TIMEOUT
+	 * of the register SDHCI_TEGRA_VENDOR_SYS_SW_CTRL.
+	 *
+	 * USE_TMCLK_FOR_DATA_TIMEOUT bit default is set to 1 and SDMMC uses
+	 * 12Mhz TMCLK which is advertised in host capability register.
+	 * With TMCLK of 12Mhz provides maximum data timeout period that can
+	 * be achieved is 11s better than using SDCLK for data timeout.
+	 *
+	 * So, TMCLK is set to 12Mhz and kept enabled all the time on SoC's
+	 * supporting separate TMCLK.
+	 *
+	 * Old device tree has single sdhci clock. So with addition of TMCLK,
+	 * retrieving sdhci clock by "sdhci" clock name based on number of
+	 * clocks in sdhci device node.
+	 */
+
+	if (of_clk_get_parent_count(pdev->dev.of_node) == 1) {
+		if (soc_data->nvquirks & NVQUIRK_HAS_TMCLK)
+			dev_warn(&pdev->dev,
+				 "missing tmclk in the device tree\n");
+
+		clk = devm_clk_get(&pdev->dev, NULL);
+		if (IS_ERR(clk)) {
+			rc = PTR_ERR(clk);
 
-		if (rc != -EPROBE_DEFER)
-			dev_err(&pdev->dev, "failed to get clock: %d\n", rc);
+			if (rc != -EPROBE_DEFER)
+				dev_err(&pdev->dev,
+					"failed to get sdhci clock: %d\n", rc);
 
-		goto err_clk_get;
+			goto err_power_req;
+		}
+	} else {
+		if (soc_data->nvquirks & NVQUIRK_HAS_TMCLK) {
+			clk = devm_clk_get(&pdev->dev, "tmclk");
+			if (IS_ERR(clk)) {
+				rc = PTR_ERR(clk);
+				if (rc == -EPROBE_DEFER)
+					goto err_power_req;
+
+				dev_warn(&pdev->dev,
+					 "failed to get tmclk: %d\n", rc);
+				clk = NULL;
+			}
+
+			clk_set_rate(clk, 12000000);
+			rc = clk_prepare_enable(clk);
+			if (rc) {
+				dev_err(&pdev->dev,
+					"failed to enable tmclk: %d\n", rc);
+				goto err_power_req;
+			}
+
+			tegra_host->tmclk = clk;
+		}
+
+		clk = devm_clk_get(&pdev->dev, "sdhci");
+		if (IS_ERR(clk)) {
+			rc = PTR_ERR(clk);
+
+			if (rc != -EPROBE_DEFER)
+				dev_err(&pdev->dev,
+					"failed to get sdhci clock: %d\n", rc);
+
+			goto err_clk_get;
+		}
 	}
+
 	clk_prepare_enable(clk);
 	pltfm_host->clk = clk;
 
@@ -1654,6 +1726,7 @@ static int sdhci_tegra_probe(struct platform_device *pdev)
 err_rst_get:
 	clk_disable_unprepare(pltfm_host->clk);
 err_clk_get:
+	clk_disable_unprepare(tegra_host->tmclk);
 err_power_req:
 err_parse_dt:
 	sdhci_pltfm_free(pdev);
@@ -1671,6 +1744,7 @@ static int sdhci_tegra_remove(struct platform_device *pdev)
 	reset_control_assert(tegra_host->rst);
 	usleep_range(2000, 4000);
 	clk_disable_unprepare(pltfm_host->clk);
+	clk_disable_unprepare(tegra_host->tmclk);
 
 	sdhci_pltfm_free(pdev);
 
-- 
2.7.4

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