[PATCH v2 20/30] mci: imx-esdhc: add support for setting drive strength
Ahmad Fatoum
a.fatoum at pengutronix.de
Wed May 7 01:21:59 PDT 2025
With increasing clock rates, drive strength may need to be reduced. Add
support for that to the i.MX eSDHC driver and to the core.
Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
drivers/mci/imx-esdhc.c | 2 ++
drivers/mci/mci-core.c | 40 ++++++++++++++++++++++++++++++++++++++--
drivers/mci/sdhci.c | 29 +++++++++++++++++++++++++++++
drivers/mci/sdhci.h | 6 ++++++
include/mci.h | 10 ++++++++++
5 files changed, 85 insertions(+), 2 deletions(-)
diff --git a/drivers/mci/imx-esdhc.c b/drivers/mci/imx-esdhc.c
index 5416d0648fa8..3871f85ea6d6 100644
--- a/drivers/mci/imx-esdhc.c
+++ b/drivers/mci/imx-esdhc.c
@@ -207,6 +207,8 @@ static void esdhc_set_ios(struct mci_host *mci, struct mci_ios *ios)
/* Set the clock speed */
set_sysctl(mci, ios->clock, mci_timing_is_ddr(ios->timing));
+ sdhci_set_drv_type(&host->sdhci, ios->drv_type);
+
/* Set the bus width */
esdhc_clrbits32(host, SDHCI_HOST_CONTROL__POWER_CONTROL__BLOCK_GAP_CONTROL,
PROCTL_DTW_4 | PROCTL_DTW_8);
diff --git a/drivers/mci/mci-core.c b/drivers/mci/mci-core.c
index f123fce59cb1..80b3496a280a 100644
--- a/drivers/mci/mci-core.c
+++ b/drivers/mci/mci-core.c
@@ -1626,6 +1626,28 @@ int mci_send_abort_tuning(struct mci *mci, u32 opcode)
}
EXPORT_SYMBOL_GPL(mci_send_abort_tuning);
+static void mmc_select_driver_type(struct mci *mci)
+{
+ int card_drv_type, drive_strength;
+ int fixed_drv_type = mci->host->fixed_drv_type;
+
+ card_drv_type = mci->ext_csd[EXT_CSD_DRIVER_STRENGTH] |
+ mmc_driver_type_mask(0);
+
+ if (mci->host->fixed_drv_type_valid)
+ drive_strength = card_drv_type & mmc_driver_type_mask(fixed_drv_type)
+ ? fixed_drv_type : 0;
+ else
+ drive_strength = 0;
+
+ mci->host->drive_strength = drive_strength;
+
+ /* Linux only sets the drive strength immediately if the driver
+ * implements select_drive_strength, which none of our drivers
+ * do yet
+ */
+}
+
static void mmc_select_max_dtr(struct mci *mci)
{
u8 card_type = mci->ext_csd[EXT_CSD_DEVICE_TYPE];
@@ -1698,6 +1720,8 @@ static int mmc_select_hs200(struct mci *mci)
int err = -EINVAL;
u8 val;
+ mmc_select_driver_type(mci);
+
/*
* Set the bus width(4 or 8) with host's support and
* switch to HS200 mode if bus width is set successfully.
@@ -1705,8 +1729,7 @@ static int mmc_select_hs200(struct mci *mci)
/* find out maximum bus width and then try DDR if supported */
err = mci_mmc_select_bus_width(mci);
if (err > 0) {
- /* TODO actually set drive strength instead of 0. Currently unsupported. */
- val = EXT_CSD_TIMING_HS200 | 0 << EXT_CSD_DRV_STR_SHIFT;
+ val = EXT_CSD_TIMING_HS200 | (mci->host->drive_strength << EXT_CSD_DRV_STR_SHIFT);
err = mci_switch(mci, EXT_CSD_HS_TIMING, val);
if (err == -EIO)
return -EBADMSG;
@@ -3095,6 +3118,8 @@ void mci_of_parse_node(struct mci_host *host,
if (of_property_read_bool(np, "no-mmc"))
host->caps2 |= MMC_CAP2_NO_MMC;
if (IS_ENABLED(CONFIG_MCI_TUNING)) {
+ u32 drv_type;
+
if (of_property_read_bool(np, "mmc-hs200-1_8v"))
host->caps2 |= MMC_CAP2_HS200_1_8V_SDR;
if (of_property_read_bool(np, "mmc-hs200-1_2v"))
@@ -3119,6 +3144,17 @@ void mci_of_parse_node(struct mci_host *host,
*/
host->caps2 &= ~(MMC_CAP2_HSX00_1_8V | MMC_CAP2_HS400_ES);
}
+
+ /* Must be after "non-removable" check */
+ if (of_property_read_u32(np, "fixed-emmc-driver-type", &drv_type) == 0) {
+ if (host->non_removable) {
+ host->fixed_drv_type = drv_type;
+ host->fixed_drv_type_valid = true;
+ } else {
+ dev_err(host->hw_dev,
+ "can't use fixed driver type, media is removable\n");
+ }
+ }
}
}
diff --git a/drivers/mci/sdhci.c b/drivers/mci/sdhci.c
index 55709e831a28..b86b3f3d8d1c 100644
--- a/drivers/mci/sdhci.c
+++ b/drivers/mci/sdhci.c
@@ -887,6 +887,35 @@ void sdhci_set_clock(struct sdhci *host, unsigned int clock, unsigned int input_
sdhci_enable_clk(host, clk);
}
+void sdhci_set_drv_type(struct sdhci *host, unsigned drv_type)
+{
+ u16 ctrl_2;
+
+ if (host->preset_enabled)
+ return;
+
+ /*
+ * We only need to set Driver Strength if the
+ * preset value enable is not set.
+ */
+ ctrl_2 = sdhci_read16(host, SDHCI_HOST_CONTROL2);
+ ctrl_2 &= ~SDHCI_CTRL_DRV_TYPE_MASK;
+ if (drv_type == MMC_SET_DRIVER_TYPE_A)
+ ctrl_2 |= SDHCI_CTRL_DRV_TYPE_A;
+ else if (drv_type == MMC_SET_DRIVER_TYPE_B)
+ ctrl_2 |= SDHCI_CTRL_DRV_TYPE_B;
+ else if (drv_type == MMC_SET_DRIVER_TYPE_C)
+ ctrl_2 |= SDHCI_CTRL_DRV_TYPE_C;
+ else if (drv_type == MMC_SET_DRIVER_TYPE_D)
+ ctrl_2 |= SDHCI_CTRL_DRV_TYPE_D;
+ else {
+ dev_warn(sdhci_dev(host), "invalid driver type, default to driver type B\n");
+ ctrl_2 |= SDHCI_CTRL_DRV_TYPE_B;
+ }
+
+ sdhci_write16(host, ctrl_2, SDHCI_HOST_CONTROL2);
+}
+
static void sdhci_do_enable_v4_mode(struct sdhci *host)
{
u16 ctrl2;
diff --git a/drivers/mci/sdhci.h b/drivers/mci/sdhci.h
index 12ab8d148144..31edebab1262 100644
--- a/drivers/mci/sdhci.h
+++ b/drivers/mci/sdhci.h
@@ -133,6 +133,11 @@
#define SDHCI_CTRL_UHS_SDR104 0x3
#define SDHCI_CTRL_UHS_DDR50 0x4
#define SDHCI_CTRL_HS400 0x5 /* Non-standard */
+#define SDHCI_CTRL_DRV_TYPE_MASK GENMASK(5, 4)
+#define SDHCI_CTRL_DRV_TYPE_B 0x0000
+#define SDHCI_CTRL_DRV_TYPE_A 0x0010
+#define SDHCI_CTRL_DRV_TYPE_C 0x0020
+#define SDHCI_CTRL_DRV_TYPE_D 0x0030
#define SDHCI_CTRL_EXEC_TUNING BIT(6)
#define SDHCI_CTRL_TUNED_CLK BIT(7)
#define SDHCI_CTRL_64BIT_ADDR BIT(13)
@@ -337,6 +342,7 @@ u16 sdhci_calc_clk(struct sdhci *host, unsigned int clock,
unsigned int *actual_clock, unsigned int input_clock);
void sdhci_set_clock(struct sdhci *host, unsigned int clock, unsigned int input_clock);
void sdhci_enable_clk(struct sdhci *host, u16 clk);
+void sdhci_set_drv_type(struct sdhci *host, unsigned drv_type);
void sdhci_enable_v4_mode(struct sdhci *host);
int sdhci_setup_host(struct sdhci *host);
void __sdhci_read_caps(struct sdhci *host, const u16 *ver,
diff --git a/include/mci.h b/include/mci.h
index af56f453704e..29aaecb46305 100644
--- a/include/mci.h
+++ b/include/mci.h
@@ -208,6 +208,8 @@
#define SD_ERASE_ARG 0x00000000
#define SD_DISCARD_ARG 0x00000001
+#define mmc_driver_type_mask(n) (1 << (n))
+
/*
* EXT_CSD fields
*/
@@ -560,6 +562,7 @@ struct mci_ios {
unsigned int clock; /* clock rate */
enum mci_bus_width bus_width; /* data bus width */
enum mci_timing timing; /* timing specification used */
+ unsigned char drv_type; /* driver type (A, B, C, D) */
};
struct mci;
@@ -632,6 +635,13 @@ struct mci_host {
int broken_cd; /**< card detect is broken */
bool non_removable; /**< device is non removable */
bool disable_wp; /**< ignore write-protect detection logic */
+ bool fixed_drv_type_valid;
+ unsigned char fixed_drv_type; /**< fixed driver type for non-removable media */
+ unsigned char drive_strength; /**< driver type (A, B, C, D) */
+#define MMC_SET_DRIVER_TYPE_B 0
+#define MMC_SET_DRIVER_TYPE_A 1
+#define MMC_SET_DRIVER_TYPE_C 2
+#define MMC_SET_DRIVER_TYPE_D 3
struct regulator *supply;
struct mci_ops ops;
};
--
2.39.5
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