drivers: nvmem: Fix voltage settings for QTI qfprom-efuse

QFPROM controller hardware requires 1.8V min for fuse blowing.
So, this change sets the voltage to 1.8V, required to blow the fuse
for qfprom-efuse controller.

To disable fuse blowing, we set the voltage to 0V since this may
be a shared rail and may be able to run at a lower rate when we're
not blowing fuses.

Fixes: 93b4e49f8c86 ("nvmem: qfprom: Add fuse blowing support")
Reported-by: Douglas Anderson <dianders@chromium.org>
Suggested-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Ravi Kumar Bokka <rbokka@codeaurora.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20210330111241.19401-4-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/nvmem/qfprom.c b/drivers/nvmem/qfprom.c
index 6cace24dfbf734d0917fe06e01eed07d59fdb5cb..100d69d8f2e1c8d689e85d6f9a2e5132ecf43e7e 100644 (file)
--- a/drivers/nvmem/qfprom.c
+++ b/drivers/nvmem/qfprom.c
@@ -127,6 +127,16 @@ static void qfprom_disable_fuse_blowing(const struct qfprom_priv *priv,
 {
        int ret;
 
+       /*
+        * This may be a shared rail and may be able to run at a lower rate
+        * when we're not blowing fuses.  At the moment, the regulator framework
+        * applies voltage constraints even on disabled rails, so remove our
+        * constraints and allow the rail to be adjusted by other users.
+        */
+       ret = regulator_set_voltage(priv->vcc, 0, INT_MAX);
+       if (ret)
+               dev_warn(priv->dev, "Failed to set 0 voltage (ignoring)\n");
+
        ret = regulator_disable(priv->vcc);
        if (ret)
                dev_warn(priv->dev, "Failed to disable regulator (ignoring)\n");
@@ -172,6 +182,17 @@ static int qfprom_enable_fuse_blowing(const struct qfprom_priv *priv,
                goto err_clk_prepared;
        }
 
+       /*
+        * Hardware requires 1.8V min for fuse blowing; this may be
+        * a rail shared do don't specify a max--regulator constraints
+        * will handle.
+        */
+       ret = regulator_set_voltage(priv->vcc, 1800000, INT_MAX);
+       if (ret) {
+               dev_err(priv->dev, "Failed to set 1.8 voltage\n");
+               goto err_clk_rate_set;
+       }
+
        ret = regulator_enable(priv->vcc);
        if (ret) {
                dev_err(priv->dev, "Failed to enable regulator\n");