[U-Boot] [PATCH v2 4/4] pinctrl: stm32: make pinctrl use hwspinlock

[Benjamin Gaignard]

From: Benjamin Gaignard <benjamin.gaignard at linaro.org>

Protect configuration registers with a hardware spinlock.

If a hwspinlock is defined in the device-tree node used it
to be sure that none of the others processors on the SoC could
change the configuration at the same time.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard at linaro.org>
---
version 2:
- be more verbose in commit message
- log the error after hwspinlock_get_by_index()

 arch/arm/dts/stm32mp157c-ed1.dts |  4 ++++
 drivers/pinctrl/pinctrl_stm32.c  | 27 +++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/arch/arm/dts/stm32mp157c-ed1.dts b/arch/arm/dts/stm32mp157c-ed1.dts
index fc277dd7d2..7a9b742d36 100644
--- a/arch/arm/dts/stm32mp157c-ed1.dts
+++ b/arch/arm/dts/stm32mp157c-ed1.dts
@@ -369,6 +369,10 @@
 	status = "okay";
 };
 
+&pinctrl {
+	hwlocks = <&hwspinlock 0>;
+};
+
 &usbphyc_port0 {
 	phy-supply = <&vdd_usb>;
 	vdda1v1-supply = <&reg11>;
diff --git a/drivers/pinctrl/pinctrl_stm32.c b/drivers/pinctrl/pinctrl_stm32.c
index 31285cdd57..5b63a2de15 100644
--- a/drivers/pinctrl/pinctrl_stm32.c
+++ b/drivers/pinctrl/pinctrl_stm32.c
@@ -1,6 +1,7 @@
 #include <common.h>
 #include <dm.h>
 #include <dm/pinctrl.h>
+#include <hwspinlock.h>
 #include <asm/arch/gpio.h>
 #include <asm/gpio.h>
 #include <asm/io.h>
@@ -19,12 +20,20 @@ static int stm32_gpio_config(struct gpio_desc *desc,
 {
 	struct stm32_gpio_priv *priv = dev_get_priv(desc->dev);
 	struct stm32_gpio_regs *regs = priv->regs;
+	struct hwspinlock *hws = dev_get_priv(desc->dev->parent);
 	u32 index;
+	int ret;
 
 	if (!ctl || ctl->af > 15 || ctl->mode > 3 || ctl->otype > 1 ||
 	    ctl->pupd > 2 || ctl->speed > 3)
 		return -EINVAL;
 
+	ret = hwspinlock_lock_timeout(hws, 1);
+	if (ret == -ETIME) {
+		dev_err(desc->dev, "HWSpinlock timeout\n");
+		return ret;
+	}
+
 	index = (desc->offset & 0x07) * 4;
 	clrsetbits_le32(&regs->afr[desc->offset >> 3], AFR_MASK << index,
 			ctl->af << index);
@@ -39,6 +48,8 @@ static int stm32_gpio_config(struct gpio_desc *desc,
 	index = desc->offset;
 	clrsetbits_le32(&regs->otyper, OTYPE_MSK << index, ctl->otype << index);
 
+	hwspinlock_unlock(hws);
+
 	return 0;
 }
 
@@ -176,6 +187,20 @@ static int stm32_pinctrl_set_state_simple(struct udevice *dev,
 }
 #endif /* PINCTRL_FULL */
 
+static int stm32_pinctrl_probe(struct udevice *dev)
+{
+	struct hwspinlock *hws = dev_get_priv(dev);
+	int err;
+
+	/* hwspinlock property is optional, just log the error */
+	err = hwspinlock_get_by_index(dev, 0, hws);
+	if (err)
+		debug("%s: hwspinlock_get_by_index may have failed (%d)\n",
+		      __func__, err);
+
+	return 0;
+}
+
 static struct pinctrl_ops stm32_pinctrl_ops = {
 #if CONFIG_IS_ENABLED(PINCTRL_FULL)
 	.set_state		= stm32_pinctrl_set_state,
@@ -200,4 +225,6 @@ U_BOOT_DRIVER(pinctrl_stm32) = {
 	.of_match	= stm32_pinctrl_ids,
 	.ops		= &stm32_pinctrl_ops,
 	.bind		= dm_scan_fdt_dev,
+	.probe		= stm32_pinctrl_probe,
+	.priv_auto_alloc_size = sizeof(struct hwspinlock),
 };
-- 
2.15.0