pinctrl: qcom: disable GPIO groups with no pins

pinctrl-msm only accepts an array of GPIOs from 0 to n-1, and it expects
each group to support have only one pin (npins == 1).

We can support "sparse" GPIO maps if we allow for some groups to have zero
pins (npins == 0).  These pins are "hidden" from the rest of the driver
and gpiolib.

Access to unavailable GPIOs is blocked via a request callback.  If the
requested GPIO is unavailable, -EACCES is returned, which prevents
further access to that GPIO.

Signed-off-by: Timur Tabi <timur@codeaurora.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 23 insertions, 5 deletions

diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c b/drivers/pinctrl/qcom/pinctrl-msm.c
index 7a960590ecaa..d45b4c2b5af1 100644
--- a/drivers/pinctrl/qcom/pinctrl-msm.c
+++ b/drivers/pinctrl/qcom/pinctrl-msm.c
@@ -507,6 +507,11 @@ static void msm_gpio_dbg_show_one(struct seq_file *s,
         };
 
         g = &pctrl->soc->groups[offset];
+
+        /* If the GPIO group has no pins, then don't show it. */
+        if (!g->npins)
+                return;
+
         ctl_reg = readl(pctrl->regs + g->ctl_reg);
 
         is_out = !!(ctl_reg & BIT(g->oe_bit));
@@ -516,7 +521,7 @@ static void msm_gpio_dbg_show_one(struct seq_file *s,
 
         seq_printf(s, " %-8s: %-3s %d", g->name, is_out ? "out" : "in", func);
         seq_printf(s, " %dmA", msm_regval_to_drive(drive));
-        seq_printf(s, " %s", pulls[pull]);
+        seq_printf(s, " %s\n", pulls[pull]);
 }
 
 static void msm_gpio_dbg_show(struct seq_file *s, struct gpio_chip *chip)
@@ -524,23 +529,36 @@ static void msm_gpio_dbg_show(struct seq_file *s, struct gpio_chip *chip)
         unsigned gpio = chip->base;
         unsigned i;
 
-        for (i = 0; i < chip->ngpio; i++, gpio++) {
+        for (i = 0; i < chip->ngpio; i++, gpio++)
                 msm_gpio_dbg_show_one(s, NULL, chip, i, gpio);
-                seq_puts(s, "\n");
-        }
 }
 
 #else
 #define msm_gpio_dbg_show NULL
 #endif
 
+/*
+ * If the requested GPIO has no pins, then treat it as unavailable.
+ * Otherwise, call the standard request function.
+ */
+static int msm_gpio_request(struct gpio_chip *chip, unsigned int offset)
+{
+        struct msm_pinctrl *pctrl = gpiochip_get_data(chip);
+        const struct msm_pingroup *g = &pctrl->soc->groups[offset];
+
+        if (!g->npins)
+                return -EACCES;
+
+        return gpiochip_generic_request(chip, offset);
+}
+
 static const struct gpio_chip msm_gpio_template = {
         .direction_input  = msm_gpio_direction_input,
         .direction_output = msm_gpio_direction_output,
         .get_direction    = msm_gpio_get_direction,
         .get              = msm_gpio_get,
         .set              = msm_gpio_set,
-        .request          = gpiochip_generic_request,
+        .request          = msm_gpio_request,
         .free             = gpiochip_generic_free,
         .dbg_show         = msm_gpio_dbg_show,
 };