pinctrl-baytrail: add function mux checking in gpio pin request
The requested gpio pin must has the func_pin_mux field set
to GPIO function by BIOS/FW in advanced. Else, the gpio pin
request would fail. This is to ensure that we do not expose
any gpio pins which shall be used for alternate functions,
for eg: wakeup pin, I/O interfaces for LPSS, etc.
Signed-off-by: Chew, Kean Ho <kean.ho.chew@intel.com>
Signed-off-by: Chew, Chiau Ee <chiau.ee.chew@intel.com>
Reviewed-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-baytrail.c
index 665b96b..bf2b3f6 100644
--- a/drivers/pinctrl/pinctrl-baytrail.c
+++ b/drivers/pinctrl/pinctrl-baytrail.c
@@ -60,6 +60,10 @@
#define BYT_NGPIO_NCORE 28
#define BYT_NGPIO_SUS 44
+#define BYT_SCORE_ACPI_UID "1"
+#define BYT_NCORE_ACPI_UID "2"
+#define BYT_SUS_ACPI_UID "3"
+
/*
* Baytrail gpio controller consist of three separate sub-controllers called
* SCORE, NCORE and SUS. The sub-controllers are identified by their acpi UID.
@@ -102,17 +106,17 @@
static struct pinctrl_gpio_range byt_ranges[] = {
{
- .name = "1", /* match with acpi _UID in probe */
+ .name = BYT_SCORE_ACPI_UID, /* match with acpi _UID in probe */
.npins = BYT_NGPIO_SCORE,
.pins = score_pins,
},
{
- .name = "2",
+ .name = BYT_NCORE_ACPI_UID,
.npins = BYT_NGPIO_NCORE,
.pins = ncore_pins,
},
{
- .name = "3",
+ .name = BYT_SUS_ACPI_UID,
.npins = BYT_NGPIO_SUS,
.pins = sus_pins,
},
@@ -145,9 +149,41 @@
return vg->reg_base + reg_offset + reg;
}
+static bool is_special_pin(struct byt_gpio *vg, unsigned offset)
+{
+ /* SCORE pin 92-93 */
+ if (!strcmp(vg->range->name, BYT_SCORE_ACPI_UID) &&
+ offset >= 92 && offset <= 93)
+ return true;
+
+ /* SUS pin 11-21 */
+ if (!strcmp(vg->range->name, BYT_SUS_ACPI_UID) &&
+ offset >= 11 && offset <= 21)
+ return true;
+
+ return false;
+}
+
static int byt_gpio_request(struct gpio_chip *chip, unsigned offset)
{
struct byt_gpio *vg = to_byt_gpio(chip);
+ void __iomem *reg = byt_gpio_reg(chip, offset, BYT_CONF0_REG);
+ u32 value;
+ bool special;
+
+ /*
+ * In most cases, func pin mux 000 means GPIO function.
+ * But, some pins may have func pin mux 001 represents
+ * GPIO function. Only allow user to export pin with
+ * func pin mux preset as GPIO function by BIOS/FW.
+ */
+ value = readl(reg) & BYT_PIN_MUX;
+ special = is_special_pin(vg, offset);
+ if ((special && value != 1) || (!special && value)) {
+ dev_err(&vg->pdev->dev,
+ "pin %u cannot be used as GPIO.\n", offset);
+ return -EINVAL;
+ }
pm_runtime_get(&vg->pdev->dev);