[PATCH v2 4.19 7/7] sdhci: tegra: Add missing TMCLK for data timeout

[Sowjanya Komatineni]

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.

Enabling TMCLK was missed when Tegra210 support was added to the driver
in commit b5a84ecf025a ("mmc: tegra: Add Tegra210 support"),

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@xxxxxxxxxxxxxxx> # 4.19
Tested-by: Jon Hunter <jonathanh@xxxxxxxxxx>
Reviewed-by: Jon Hunter <jonathanh@xxxxxxxxxx>
Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
---
 drivers/mmc/host/sdhci-tegra.c | 48 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
index 5a7c032..ff3340c 100644
--- a/drivers/mmc/host/sdhci-tegra.c
+++ b/drivers/mmc/host/sdhci-tegra.c
@@ -56,6 +56,12 @@
 #define NVQUIRK_ENABLE_DDR50		BIT(5)
 #define NVQUIRK_HAS_PADCALIB		BIT(6)
 
+/*
+ * NVQUIRK_HAS_TMCLK is for SoC's having separate timeout clock for Tegra
+ * SDMMC hardware data timeout.
+ */
+#define NVQUIRK_HAS_TMCLK				BIT(10)
+
 struct sdhci_tegra_soc_data {
 	const struct sdhci_pltfm_data *pdata;
 	u32 nvquirks;
@@ -64,6 +70,7 @@ struct sdhci_tegra_soc_data {
 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;
 
@@ -433,6 +440,7 @@ static const struct sdhci_pltfm_data sdhci_tegra210_pdata = {
 
 static const struct sdhci_tegra_soc_data soc_data_tegra210 = {
 	.pdata = &sdhci_tegra210_pdata,
+	.nvquirks = NVQUIRK_HAS_TMCLK,
 };
 
 static const struct sdhci_pltfm_data sdhci_tegra186_pdata = {
@@ -455,6 +463,7 @@ static const struct sdhci_pltfm_data sdhci_tegra186_pdata = {
 
 static const struct sdhci_tegra_soc_data soc_data_tegra186 = {
 	.pdata = &sdhci_tegra186_pdata,
+	.nvquirks = NVQUIRK_HAS_TMCLK,
 };
 
 static const struct of_device_id sdhci_tegra_dt_match[] = {
@@ -510,6 +519,43 @@ static int sdhci_tegra_probe(struct platform_device *pdev)
 		goto err_power_req;
 	}
 
+	/*
+	 * Some Tegra SoC's has a separate SDMMC_LEGACY_TM clock used for
+	 * host 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.
+	 */
+
+	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(mmc_dev(host->mmc), NULL);
 	if (IS_ERR(clk)) {
 		dev_err(mmc_dev(host->mmc), "clk err\n");
@@ -550,6 +596,7 @@ 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);
@@ -567,6 +614,7 @@ 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