[PATCH v3 1/2] power: pmic: pca9450: Add support for system reset

[Primoz Fiser]

The family of PCA9450 PMICs have the ability to perform system resets.
Restarting via PMIC is preferred method of restarting the system as all
the peripherals are brought to a know state after a power-cycle. The
PCA9450 features a cold restart procedure which is initiated by an I2C
command 0x14 to the SW_RST register.

Support in Linux for restarting via PCA9450 PMIC has been added by
Linux commit 6157e62b07d9 ("regulator: pca9450: Add restart handler").

Now add support for it also in the U-Boot via sysreset framework.

Signed-off-by: Primoz Fiser <primoz.fiser at norik.com>
Reviewed-by: Paul Geurts <paul.geurts at prodrive-technologies.com>
---
Changes in v3:
- rebase custodians/u-boot-mmc branch: next 
- add Reviewed-by: tags

Link to v2: https://lore.kernel.org/all/20250814094741.4177431-1-primoz.fiser@norik.com/

 drivers/power/pmic/pca9450.c | 44 ++++++++++++++++++++++++++++++++++++
 include/power/pca9450.h      |  2 ++
 2 files changed, 46 insertions(+)

diff --git a/drivers/power/pmic/pca9450.c b/drivers/power/pmic/pca9450.c
index 0e3d14abf154..8b98c2239e13 100644
--- a/drivers/power/pmic/pca9450.c
+++ b/drivers/power/pmic/pca9450.c
@@ -6,13 +6,17 @@
 #include <fdtdec.h>
 #include <errno.h>
 #include <dm.h>
+#include <dm/device_compat.h>
+#include <dm/lists.h>
 #include <i2c.h>
 #include <log.h>
 #include <asm/global_data.h>
+#include <linux/delay.h>
 #include <linux/printk.h>
 #include <power/pmic.h>
 #include <power/regulator.h>
 #include <power/pca9450.h>
+#include <sysreset.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -79,6 +83,15 @@ static int pca9450_bind(struct udevice *dev)
 static int pca9450_probe(struct udevice *dev)
 {
 	unsigned int reset_ctrl;
+	int ret;
+
+	if (CONFIG_IS_ENABLED(SYSRESET)) {
+		ret = device_bind_driver_to_node(dev, "pca9450_sysreset",
+						 "pca9450_sysreset",
+						 dev_ofnode(dev), NULL);
+		if (ret)
+			return ret;
+	}
 
 	if (ofnode_read_bool(dev_ofnode(dev), "nxp,wdog_b-warm-reset"))
 		reset_ctrl = PCA9450_PMIC_RESET_WDOG_B_CFG_WARM;
@@ -112,3 +125,34 @@ U_BOOT_DRIVER(pmic_pca9450) = {
 	.probe = pca9450_probe,
 	.ops = &pca9450_ops,
 };
+
+#ifdef CONFIG_SYSRESET
+static int pca9450_sysreset_request(struct udevice *dev, enum sysreset_t type)
+{
+	u8 cmd = PCA9450_SW_RST_COLD_RST;
+
+	if (type != SYSRESET_COLD)
+		return -EPROTONOSUPPORT;
+
+	if (pmic_write(dev->parent, PCA9450_SW_RST, &cmd, 1)) {
+		dev_err(dev, "reset command failed\n");
+	} else {
+		/* tRESTART is 250ms, delay 300ms just to be sure */
+		mdelay(300);
+		/* Should not get here, warn if we do */
+		dev_warn(dev, "didn't respond to reset command\n");
+	}
+
+	return -EINPROGRESS;
+}
+
+static struct sysreset_ops pca9450_sysreset_ops = {
+	.request	= pca9450_sysreset_request,
+};
+
+U_BOOT_DRIVER(pca9450_sysreset) = {
+	.name		= "pca9450_sysreset",
+	.id		= UCLASS_SYSRESET,
+	.ops		= &pca9450_sysreset_ops,
+};
+#endif /* CONFIG_SYSRESET */
diff --git a/include/power/pca9450.h b/include/power/pca9450.h
index e5ab09fb8c83..9119ef793b1f 100644
--- a/include/power/pca9450.h
+++ b/include/power/pca9450.h
@@ -75,4 +75,6 @@ enum {
 #define PCA9450_PMIC_RESET_WDOG_B_CFG_WARM		0x40
 #define PCA9450_PMIC_RESET_WDOG_B_CFG_COLD_LDO12	0x80
 
+#define PCA9450_SW_RST_COLD_RST		0x14
+
 #endif
-- 
2.34.1