power: reset: Add TPS65086 restart driver

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>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index 4d11920..4b563db 100644 (file)
--- 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 cf3f4d0..f606a2f 100644 (file)
--- 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 (file)
index 0000000..78b89f7
--- /dev/null
+++ b/drivers/power/reset/tps65086-restart.c
@@ -0,0 +1,98 @@
+// 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 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);
+       struct tps65086 *tps65086 = dev_get_drvdata(tps65086_restart->dev->parent);
+       int ret;
+
+       ret = regmap_write(tps65086->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->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-reset", },
+       { /* 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");