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Subject[PATCH v1 3/3] power: reset: Add TPS65086 restart driver
Date
The only way to reset the BeagleV Starlight v0.9 board[1] properly is to
tell the PMIC to reset itself which will then assert the external reset
lines of the SoC, USB hub and ethernet phy.

This adds a driver to register a reset handler to do just that.

[1] https://github.com/beagleboard/beaglev-starlight

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
---
drivers/mfd/tps65086.c | 1 +
drivers/power/reset/Kconfig | 6 ++
drivers/power/reset/Makefile | 1 +
drivers/power/reset/tps65086-restart.c | 99 ++++++++++++++++++++++++++
4 files changed, 107 insertions(+)
create mode 100644 drivers/power/reset/tps65086-restart.c

diff --git a/drivers/mfd/tps65086.c b/drivers/mfd/tps65086.c
index cc3478ee9a64..1bfba0758fcc 100644
--- a/drivers/mfd/tps65086.c
+++ b/drivers/mfd/tps65086.c
@@ -24,6 +24,7 @@
static const struct mfd_cell tps65086_cells[] = {
{ .name = "tps65086-regulator", },
{ .name = "tps65086-gpio", },
+ { .name = "tps65086-restart", },
};

static const struct regmap_range tps65086_yes_ranges[] = {
diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index 4d1192062508..4b563db3ab3e 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -204,6 +204,12 @@ config POWER_RESET_ST
help
Reset support for STMicroelectronics boards.

+config POWER_RESET_TPS65086
+ bool "TPS65086 restart driver"
+ depends on MFD_TPS65086
+ help
+ This driver adds support for resetting the TPS65086 PMIC on restart.
+
config POWER_RESET_VERSATILE
bool "ARM Versatile family reboot driver"
depends on ARM
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index cf3f4d02d8a5..f606a2f60539 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o
obj-$(CONFIG_POWER_RESET_REGULATOR) += regulator-poweroff.o
obj-$(CONFIG_POWER_RESET_RESTART) += restart-poweroff.o
obj-$(CONFIG_POWER_RESET_ST) += st-poweroff.o
+obj-$(CONFIG_POWER_RESET_TPS65086) += tps65086-restart.o
obj-$(CONFIG_POWER_RESET_VERSATILE) += arm-versatile-reboot.o
obj-$(CONFIG_POWER_RESET_VEXPRESS) += vexpress-poweroff.o
obj-$(CONFIG_POWER_RESET_XGENE) += xgene-reboot.o
diff --git a/drivers/power/reset/tps65086-restart.c b/drivers/power/reset/tps65086-restart.c
new file mode 100644
index 000000000000..ad9f2c5a84ac
--- /dev/null
+++ b/drivers/power/reset/tps65086-restart.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Emil Renner Berthing
+ */
+
+#include <linux/mfd/tps65086.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+
+struct tps65086_restart {
+ struct notifier_block handler;
+ struct tps65086 *tps;
+ struct device *dev;
+};
+
+static int tps65086_restart_notify(struct notifier_block *this,
+ unsigned long mode, void *cmd)
+{
+ struct tps65086_restart *tps65086_restart =
+ container_of(this, struct tps65086_restart, handler);
+ int ret;
+
+ ret = regmap_write(tps65086_restart->tps->regmap, TPS65086_FORCESHUTDN, 1);
+ if (ret) {
+ dev_err(tps65086_restart->dev, "%s: error writing to tps65086 pmic: %d\n",
+ __func__, ret);
+ return NOTIFY_DONE;
+ }
+
+ /* give it a little time */
+ mdelay(200);
+
+ WARN_ON(1);
+
+ return NOTIFY_DONE;
+}
+
+static int tps65086_restart_probe(struct platform_device *pdev)
+{
+ struct tps65086_restart *tps65086_restart;
+ int ret;
+
+ tps65086_restart = devm_kzalloc(&pdev->dev, sizeof(*tps65086_restart), GFP_KERNEL);
+ if (!tps65086_restart)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, tps65086_restart);
+
+ tps65086_restart->handler.notifier_call = tps65086_restart_notify;
+ tps65086_restart->handler.priority = 192;
+ tps65086_restart->tps = dev_get_drvdata(pdev->dev.parent);
+ tps65086_restart->dev = &pdev->dev;
+
+ ret = register_restart_handler(&tps65086_restart->handler);
+ if (ret) {
+ dev_err(&pdev->dev, "%s: cannot register restart handler: %d\n",
+ __func__, ret);
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static int tps65086_restart_remove(struct platform_device *pdev)
+{
+ struct tps65086_restart *tps65086_restart = platform_get_drvdata(pdev);
+ int ret;
+
+ ret = unregister_restart_handler(&tps65086_restart->handler);
+ if (ret) {
+ dev_err(&pdev->dev, "%s: cannot unregister restart handler: %d\n",
+ __func__, ret);
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static const struct platform_device_id tps65086_restart_id_table[] = {
+ { "tps65086-restart", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, tps65086_restart_id_table);
+
+static struct platform_driver tps65086_restart_driver = {
+ .driver = {
+ .name = "tps65086-restart",
+ },
+ .probe = tps65086_restart_probe,
+ .remove = tps65086_restart_remove,
+ .id_table = tps65086_restart_id_table,
+};
+module_platform_driver(tps65086_restart_driver);
+
+MODULE_AUTHOR("Emil Renner Berthing <kernel@esmil.dk>");
+MODULE_DESCRIPTION("TPS65086 restart driver");
+MODULE_LICENSE("GPL v2");
--
2.32.0
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