[PATCH v6 7/7] sdhci: tegra: Add missing TMCLK for data timeout
From: Sowjanya Komatineni
Date: Wed Aug 26 2020 - 23:50:45 EST
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@xxxxxxxxxxxxxxx> # 5.4
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 | 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