eSDHC supports signal voltage switch from 3.3v to 1.8v by
eSDHC_PROCTL[VOLT_SEL] bit. This bit changes the value of output
signal SDHC_VS, and there must be a control circuit out of eSDHC
to change the signal voltage according to SDHC_VS output signal.
Signed-off-by: Yangbo Lu <yangbo.lu@xxxxxxx>
---
Changes for v2:
- Used Adrain's method to support voltage switching:
host->mmc_host_ops.start_signal_voltage_switch =
esdhc_signal_voltage_switch;
Changes for v3:
- Put .start_signal_voltage_switch assigning after IS_ERR(host) check.
Changes for v4:
- None
---
drivers/mmc/host/sdhci-esdhc.h | 1 +
drivers/mmc/host/sdhci-of-esdhc.c | 74 +++++++++++++++++++++++++++++++++++++++
2 files changed, 75 insertions(+)
diff --git a/drivers/mmc/host/sdhci-esdhc.h b/drivers/mmc/host/sdhci-esdhc.h
index 5343fc0..6869567 100644
--- a/drivers/mmc/host/sdhci-esdhc.h
+++ b/drivers/mmc/host/sdhci-esdhc.h
@@ -37,6 +37,7 @@
/* Protocol Control Register */
#define ESDHC_PROCTL 0x28
+#define ESDHC_VOLT_SEL 0x00000400
#define ESDHC_CTRL_4BITBUS (0x1 << 1)
#define ESDHC_CTRL_8BITBUS (0x2 << 1)
#define ESDHC_CTRL_BUSWIDTH_MASK (0x3 << 1)
diff --git a/drivers/mmc/host/sdhci-of-esdhc.c b/drivers/mmc/host/sdhci-of-esdhc.c
index 6d024b6..4dd28c3 100644
--- a/drivers/mmc/host/sdhci-of-esdhc.c
+++ b/drivers/mmc/host/sdhci-of-esdhc.c
@@ -16,6 +16,7 @@
#include <linux/err.h>
#include <linux/io.h>
#include <linux/of.h>
+#include <linux/of_address.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/sys_soc.h>
@@ -559,6 +560,76 @@ static void esdhc_reset(struct sdhci_host *host, u8 mask)
sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);
}
+/* The SCFG, Supplemental Configuration Unit, provides SoC specific
+ * configuration and status registers for the device. There is a
+ * SDHC IO VSEL control register on SCFG for some platforms. It's
+ * used to support SDHC IO voltage switching.
+ */
+static const struct of_device_id scfg_device_ids[] = {
+ { .compatible = "fsl,t1040-scfg", },
+ { .compatible = "fsl,ls1012a-scfg", },
+ { .compatible = "fsl,ls1046a-scfg", },
+ {}
+};
+
+/* SDHC IO VSEL control register definition */
+#define SCFG_SDHCIOVSELCR 0x408
+#define SDHCIOVSELCR_TGLEN 0x80000000
+#define SDHCIOVSELCR_VSELVAL 0x60000000
+#define SDHCIOVSELCR_SDHC_VS 0x00000001
+
+static int esdhc_signal_voltage_switch(struct mmc_host *mmc,
+ struct mmc_ios *ios)
+{
+ struct sdhci_host *host = mmc_priv(mmc);
+ struct device_node *scfg_node;
+ void __iomem *scfg_base = NULL;
+ u32 sdhciovselcr;
+ u32 val;
+
+ /*
+ * Signal Voltage Switching is only applicable for Host Controllers
+ * v3.00 and above.
+ */
+ if (host->version < SDHCI_SPEC_300)
+ return 0;
+
+ val = sdhci_readl(host, ESDHC_PROCTL);
+
+ switch (ios->signal_voltage) {
+ case MMC_SIGNAL_VOLTAGE_330:
+ val &= ~ESDHC_VOLT_SEL;
+ sdhci_writel(host, val, ESDHC_PROCTL);
+ return 0;
+ case MMC_SIGNAL_VOLTAGE_180:
+ scfg_node = of_find_matching_node(NULL, scfg_device_ids);
+ if (scfg_node)
+ scfg_base = of_iomap(scfg_node, 0);
+ if (scfg_base) {
+ sdhciovselcr = SDHCIOVSELCR_TGLEN |
+ SDHCIOVSELCR_VSELVAL;
+ iowrite32be(sdhciovselcr,
+ scfg_base + SCFG_SDHCIOVSELCR);
+
+ val |= ESDHC_VOLT_SEL;
+ sdhci_writel(host, val, ESDHC_PROCTL);
+ mdelay(5);
+
+ sdhciovselcr = SDHCIOVSELCR_TGLEN |
+ SDHCIOVSELCR_SDHC_VS;
+ iowrite32be(sdhciovselcr,
+ scfg_base + SCFG_SDHCIOVSELCR);
+ iounmap(scfg_base);
+ } else {
+ val |= ESDHC_VOLT_SEL;
+ sdhci_writel(host, val, ESDHC_PROCTL);
+ }
+ return 0;
+ default:
+ return 0;
+ }
+}
+
#ifdef CONFIG_PM_SLEEP
static u32 esdhc_proctl;
static int esdhc_of_suspend(struct device *dev)
@@ -716,6 +787,9 @@ static int sdhci_esdhc_probe(struct platform_device *pdev)
if (IS_ERR(host))
return PTR_ERR(host);
+ host->mmc_host_ops.start_signal_voltage_switch =
+ esdhc_signal_voltage_switch;
+
esdhc_init(pdev, host);
sdhci_get_of_property(pdev);
--
2.1.0.27.g96db324
--
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