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Subject[PATCH 07/13] power: reset: Add a driver for the Microsemi Ocelot reset
Date
The Microsemi Ocelot SoC has a register allowing to reset the MIPS core.
Unfortunately, the syscon-reboot driver can't be used directly (but almost)
as the reset control may be disabled using another register.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
---
To: Sebastian Reichel <sre@kernel.org>
Cc: linux-pm@vger.kernel.org

drivers/power/reset/Kconfig | 7 +++
drivers/power/reset/Makefile | 1 +
drivers/power/reset/ocelot-reset.c | 87 ++++++++++++++++++++++++++++++++++++++
3 files changed, 95 insertions(+)
create mode 100644 drivers/power/reset/ocelot-reset.c

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index ca0de1a78e85..2372f8e1040d 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -113,6 +113,13 @@ config POWER_RESET_MSM
help
Power off and restart support for Qualcomm boards.

+config POWER_RESET_OCELOT_RESET
+ bool "Microsemi Ocelot reset driver"
+ depends on MSCC_OCELOT || COMPILE_TEST
+ select MFD_SYSCON
+ help
+ This driver supports restart for Microsemi Ocelot SoC.
+
config POWER_RESET_PIIX4_POWEROFF
tristate "Intel PIIX4 power-off driver"
depends on PCI
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index aeb65edb17b7..df9d92291c67 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_POWER_RESET_GPIO_RESTART) += gpio-restart.o
obj-$(CONFIG_POWER_RESET_HISI) += hisi-reboot.o
obj-$(CONFIG_POWER_RESET_IMX) += imx-snvs-poweroff.o
obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o
+obj-$(CONFIG_POWER_RESET_OCELOT_RESET) += ocelot-reset.o
obj-$(CONFIG_POWER_RESET_PIIX4_POWEROFF) += piix4-poweroff.o
obj-$(CONFIG_POWER_RESET_LTC2952) += ltc2952-poweroff.o
obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o
diff --git a/drivers/power/reset/ocelot-reset.c b/drivers/power/reset/ocelot-reset.c
new file mode 100644
index 000000000000..d27e3d51f6a4
--- /dev/null
+++ b/drivers/power/reset/ocelot-reset.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/*
+ * Microsemi MIPS SoC reset driver
+ *
+ * License: Dual MIT/GPL
+ * Copyright (c) 2017 Microsemi Corporation
+ */
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/notifier.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+
+struct ocelot_reset_context {
+ struct regmap *chip_regs;
+ struct regmap *cpu_ctrl;
+ struct notifier_block restart_handler;
+};
+
+#define ICPU_CFG_CPU_SYSTEM_CTRL_RESET 0x20
+#define CORE_RST_PROTECT BIT(2)
+
+#define CHIP_REGS_SOFT_RST 0x8
+#define SOFT_CHIP_RST BIT(0)
+
+static int ocelot_restart_handle(struct notifier_block *this,
+ unsigned long mode, void *cmd)
+{
+ struct ocelot_reset_context *ctx = container_of(this, struct
+ ocelot_reset_context,
+ restart_handler);
+
+ /* Make sure the core is not protected from reset */
+ regmap_update_bits(ctx->cpu_ctrl, ICPU_CFG_CPU_SYSTEM_CTRL_RESET,
+ CORE_RST_PROTECT, 0);
+
+ regmap_write(ctx->chip_regs, CHIP_REGS_SOFT_RST, SOFT_CHIP_RST);
+
+ pr_emerg("Unable to restart system\n");
+ return NOTIFY_DONE;
+}
+
+static int ocelot_reset_probe(struct platform_device *pdev)
+{
+ struct ocelot_reset_context *ctx;
+ struct device *dev = &pdev->dev;
+ int err;
+
+ ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+
+ ctx->chip_regs = syscon_node_to_regmap(of_get_parent(dev->of_node));
+ if (IS_ERR(ctx->chip_regs))
+ return PTR_ERR(ctx->chip_regs);
+
+ ctx->cpu_ctrl = syscon_regmap_lookup_by_phandle(dev->of_node,
+ "mscc,cpucontrol");
+ if (IS_ERR(ctx->cpu_ctrl))
+ return PTR_ERR(ctx->cpu_ctrl);
+
+ ctx->restart_handler.notifier_call = ocelot_restart_handle;
+ ctx->restart_handler.priority = 192;
+ err = register_restart_handler(&ctx->restart_handler);
+ if (err)
+ dev_err(dev, "can't register restart notifier (err=%d)\n", err);
+
+ return err;
+}
+
+static const struct of_device_id ocelot_reset_of_match[] = {
+ { .compatible = "mscc,ocelot-chip-reset" },
+ {}
+};
+
+static struct platform_driver ocelot_reset_driver = {
+ .probe = ocelot_reset_probe,
+ .driver = {
+ .name = "ocelot-chip-reset",
+ .of_match_table = ocelot_reset_of_match,
+ },
+};
+builtin_platform_driver(ocelot_reset_driver);
--
2.15.0
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