[PATCH 2/3] [v8] pinctrl: qcom: disable GPIO groups with no pins

Timur Tabi
2017-12-13T18:30:17Z

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>
---
drivers/pinctrl/qcom/pinctrl-msm.c | 28 +++++++++++++++++++++++-----
1 file 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,
};