reset: Add support for resets provided by SCMI

On some ARM based systems, a separate Cortex-M based System Control
Processor(SCP) provides the overall power, clock, reset and system
control. System Control and Management Interface(SCMI) Message Protocol
is defined for the communication between the Application Cores(AP)
and the SCP.

Adds support for the resets provided using SCMI protocol for performing
reset management of various devices present on the SoC. Various reset
functionalities are achieved by the means of different ARM SCMI device
operations provided by the ARM SCMI framework.

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

diff --git a/MAINTAINERS b/MAINTAINERS
index 783569e3c4b48752c3555e9bee6fbc87adad5117..59df8f88b56de121d4e342d6610a8bdefabdcbde 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15545,6 +15545,7 @@ F:      drivers/clk/clk-sc[mp]i.c
 F:     drivers/cpufreq/sc[mp]i-cpufreq.c
 F:     drivers/firmware/arm_scpi.c
 F:     drivers/firmware/arm_scmi/
+F:     drivers/reset/reset-scmi.c
 F:     include/linux/sc[mp]i_protocol.h
 
 SYSTEM RESET/SHUTDOWN DRIVERS

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index 21efb7d39d627b07907b49d3156419a70eca2d34..4178ac11ba85570e79ed9d8b85b2e7673e0f6001 100644 (file)
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -116,6 +116,17 @@ config RESET_QCOM_PDC
          to control reset signals provided by PDC for Modem, Compute,
          Display, GPU, Debug, AOP, Sensors, Audio, SP and APPS.
 
+config RESET_SCMI
+       tristate "Reset driver controlled via ARM SCMI interface"
+       depends on ARM_SCMI_PROTOCOL || COMPILE_TEST
+       default ARM_SCMI_PROTOCOL
+       help
+         This driver provides support for reset signal/domains that are
+         controlled by firmware that implements the SCMI interface.
+
+         This driver uses SCMI Message Protocol to interact with the
+         firmware controlling all the reset signals.
+
 config RESET_SIMPLE
        bool "Simple Reset Controller Driver" if COMPILE_TEST
        default ARCH_STM32 || ARCH_STRATIX10 || ARCH_SUNXI || ARCH_ZX || ARCH_ASPEED || ARCH_BITMAIN

diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 61456b8f659c08bad5431270398973fb867a2fb7..cf60ce526064be30f562e2408cca62651fa72fce 100644 (file)
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_RESET_OXNAS) += reset-oxnas.o
 obj-$(CONFIG_RESET_PISTACHIO) += reset-pistachio.o
 obj-$(CONFIG_RESET_QCOM_AOSS) += reset-qcom-aoss.o
 obj-$(CONFIG_RESET_QCOM_PDC) += reset-qcom-pdc.o
+obj-$(CONFIG_RESET_SCMI) += reset-scmi.o
 obj-$(CONFIG_RESET_SIMPLE) += reset-simple.o
 obj-$(CONFIG_RESET_STM32MP157) += reset-stm32mp1.o
 obj-$(CONFIG_RESET_SOCFPGA) += reset-socfpga.o

diff --git a/drivers/reset/reset-scmi.c b/drivers/reset/reset-scmi.c
new file mode 100644 (file)
index 0000000..c6d3c84
--- /dev/null
+++ b/drivers/reset/reset-scmi.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ARM System Control and Management Interface (ARM SCMI) reset driver
+ *
+ * Copyright (C) 2019 ARM Ltd.
+ */
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/device.h>
+#include <linux/reset-controller.h>
+#include <linux/scmi_protocol.h>
+
+/**
+ * struct scmi_reset_data - reset controller information structure
+ * @rcdev: reset controller entity
+ * @handle: ARM SCMI handle used for communication with system controller
+ */
+struct scmi_reset_data {
+       struct reset_controller_dev rcdev;
+       const struct scmi_handle *handle;
+};
+
+#define to_scmi_reset_data(p)  container_of((p), struct scmi_reset_data, rcdev)
+#define to_scmi_handle(p)      (to_scmi_reset_data(p)->handle)
+
+/**
+ * scmi_reset_assert() - assert device reset
+ * @rcdev: reset controller entity
+ * @id: ID of the reset to be asserted
+ *
+ * This function implements the reset driver op to assert a device's reset
+ * using the ARM SCMI protocol.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int
+scmi_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+       const struct scmi_handle *handle = to_scmi_handle(rcdev);
+
+       return handle->reset_ops->assert(handle, id);
+}
+
+/**
+ * scmi_reset_deassert() - deassert device reset
+ * @rcdev: reset controller entity
+ * @id: ID of the reset to be deasserted
+ *
+ * This function implements the reset driver op to deassert a device's reset
+ * using the ARM SCMI protocol.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int
+scmi_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+       const struct scmi_handle *handle = to_scmi_handle(rcdev);
+
+       return handle->reset_ops->deassert(handle, id);
+}
+
+/**
+ * scmi_reset_reset() - reset the device
+ * @rcdev: reset controller entity
+ * @id: ID of the reset signal to be reset(assert + deassert)
+ *
+ * This function implements the reset driver op to trigger a device's
+ * reset signal using the ARM SCMI protocol.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int
+scmi_reset_reset(struct reset_controller_dev *rcdev, unsigned long id)
+{
+       const struct scmi_handle *handle = to_scmi_handle(rcdev);
+
+       return handle->reset_ops->reset(handle, id);
+}
+
+static const struct reset_control_ops scmi_reset_ops = {
+       .assert         = scmi_reset_assert,
+       .deassert       = scmi_reset_deassert,
+       .reset          = scmi_reset_reset,
+};
+
+static int scmi_reset_probe(struct scmi_device *sdev)
+{
+       struct scmi_reset_data *data;
+       struct device *dev = &sdev->dev;
+       struct device_node *np = dev->of_node;
+       const struct scmi_handle *handle = sdev->handle;
+
+       if (!handle || !handle->reset_ops)
+               return -ENODEV;
+
+       data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+       if (!data)
+               return -ENOMEM;
+
+       data->rcdev.ops = &scmi_reset_ops;
+       data->rcdev.owner = THIS_MODULE;
+       data->rcdev.of_node = np;
+       data->rcdev.nr_resets = handle->reset_ops->num_domains_get(handle);
+
+       return devm_reset_controller_register(dev, &data->rcdev);
+}
+
+static const struct scmi_device_id scmi_id_table[] = {
+       { SCMI_PROTOCOL_RESET },
+       { },
+};
+MODULE_DEVICE_TABLE(scmi, scmi_id_table);
+
+static struct scmi_driver scmi_reset_driver = {
+       .name = "scmi-reset",
+       .probe = scmi_reset_probe,
+       .id_table = scmi_id_table,
+};
+module_scmi_driver(scmi_reset_driver);
+
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCMI reset controller driver");
+MODULE_LICENSE("GPL v2");