mmc: sdhci-of-k1: add regulator and pinctrl voltage switching support

Add voltage switching infrastructure for UHS-I modes by integrating both
regulator framework (for supply voltage control) and pinctrl state
switching (for pin drive strength optimization).

- Add regulator supply parsing and voltage switching callback
- Add optional pinctrl state switching between "default" (3.3V) and
  "state_uhs" (1.8V) configurations
- Enable coordinated voltage and pin configuration changes for UHS modes

This provides complete voltage switching support while maintaining
backward compatibility when pinctrl states are not defined.

Tested-by: Anand Moon <linux.amoon@gmail.com>
Tested-by: Trevor Gamblin <tgamblin@baylibre.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Troy Mitchell <troy.mitchell@linux.dev>
Tested-by: Vincent Legoll <legoll@online.fr>
Signed-off-by: Iker Pedrosa <ikerpedrosam@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/sdhci-of-k1.c b/drivers/mmc/host/sdhci-of-k1.c
index 0dd06fc19b8574ae1b00f7e5d09b7d4c87d06770..d9144537032a51a12d7480885f247f4c66583e59 100644 (file)
--- a/drivers/mmc/host/sdhci-of-k1.c
+++ b/drivers/mmc/host/sdhci-of-k1.c
@@ -16,6 +16,7 @@
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/reset.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/platform_device.h>
 
 #include "sdhci.h"
@@ -71,6 +72,9 @@
 struct spacemit_sdhci_host {
        struct clk *clk_core;
        struct clk *clk_io;
+       struct pinctrl *pinctrl;
+       struct pinctrl_state *pinctrl_default;
+       struct pinctrl_state *pinctrl_uhs;
 };
 
 /* All helper functions will update clr/set while preserve rest bits */
@@ -219,6 +223,46 @@ static void spacemit_sdhci_pre_hs400_to_hs200(struct mmc_host *mmc)
                               SPACEMIT_SDHC_PHY_CTRL_REG);
 }
 
+static int spacemit_sdhci_start_signal_voltage_switch(struct mmc_host *mmc,
+                                                     struct mmc_ios *ios)
+{
+       struct sdhci_host *host = mmc_priv(mmc);
+       struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+       struct spacemit_sdhci_host *sdhst = sdhci_pltfm_priv(pltfm_host);
+       struct pinctrl_state *state;
+       int ret;
+
+       ret = sdhci_start_signal_voltage_switch(mmc, ios);
+       if (ret)
+               return ret;
+
+       if (!sdhst->pinctrl)
+               return 0;
+
+       /* Select appropriate pinctrl state based on signal voltage */
+       switch (ios->signal_voltage) {
+       case MMC_SIGNAL_VOLTAGE_330:
+               state = sdhst->pinctrl_default;
+               break;
+       case MMC_SIGNAL_VOLTAGE_180:
+               state = sdhst->pinctrl_uhs;
+               break;
+       default:
+               dev_warn(mmc_dev(mmc), "unsupported voltage %d\n", ios->signal_voltage);
+               return 0;
+       }
+
+       ret = pinctrl_select_state(sdhst->pinctrl, state);
+       if (ret) {
+               dev_warn(mmc_dev(mmc), "failed to select pinctrl state: %d\n", ret);
+               return 0;
+       }
+       dev_dbg(mmc_dev(mmc), "switched to %s pinctrl state\n",
+               ios->signal_voltage == MMC_SIGNAL_VOLTAGE_180 ? "UHS" : "default");
+
+       return 0;
+}
+
 static inline int spacemit_sdhci_get_clocks(struct device *dev,
                                            struct sdhci_pltfm_host *pltfm_host)
 {
@@ -252,6 +296,30 @@ static inline int spacemit_sdhci_get_resets(struct device *dev)
        return 0;
 }
 
+static inline void spacemit_sdhci_get_pins(struct device *dev,
+                                          struct sdhci_pltfm_host *pltfm_host)
+{
+       struct spacemit_sdhci_host *sdhst = sdhci_pltfm_priv(pltfm_host);
+
+       sdhst->pinctrl = devm_pinctrl_get(dev);
+       if (IS_ERR(sdhst->pinctrl)) {
+               sdhst->pinctrl = NULL;
+               dev_dbg(dev, "pinctrl not available, voltage switching will work without it\n");
+               return;
+       }
+
+       sdhst->pinctrl_default = pinctrl_lookup_state(sdhst->pinctrl, "default");
+       if (IS_ERR(sdhst->pinctrl_default))
+               sdhst->pinctrl_default = NULL;
+
+       sdhst->pinctrl_uhs = pinctrl_lookup_state(sdhst->pinctrl, "uhs");
+       if (IS_ERR(sdhst->pinctrl_uhs))
+               sdhst->pinctrl_uhs = NULL;
+
+       dev_dbg(dev, "pinctrl setup: default=%p, uhs=%p\n",
+               sdhst->pinctrl_default, sdhst->pinctrl_uhs);
+}
+
 static const struct sdhci_ops spacemit_sdhci_ops = {
        .get_max_clock          = spacemit_sdhci_clk_get_max_clock,
        .reset                  = spacemit_sdhci_reset,
@@ -324,6 +392,10 @@ static int spacemit_sdhci_probe(struct platform_device *pdev)
 
        host->mmc->caps |= MMC_CAP_NEED_RSP_BUSY;
 
+       spacemit_sdhci_get_pins(dev, pltfm_host);
+
+       host->mmc_host_ops.start_signal_voltage_switch = spacemit_sdhci_start_signal_voltage_switch;
+
        ret = spacemit_sdhci_get_clocks(dev, pltfm_host);
        if (ret)
                goto err_pltfm;