[PATCH v3 2/2] reset: intel: Add system reset controller driver

Dilip Kota
2019-11-20T06:10:39Z

Add driver for the reset controller present on Intel
Gateway SoCs for performing reset management of the
devices present on the SoC. Driver also registers a
reset handler to peform the entire device reset.

Signed-off-by: Dilip Kota <eswara.kota@linux.intel.com>
---
Changes on v3:
Address review comments:
Remove intel_reset_device() as not supported
reset-intel-syscon.c renamed to reset-intel-gw.c
Remove syscon and add regmap logic
Add support to legacy xrx200 SoC
Use bitfield helper functions for bit operations.
Change config RESET_INTEL_SYSCON-> RESET_INTEL_GW

drivers/reset/Kconfig | 9 ++
drivers/reset/Makefile | 1 +
drivers/reset/reset-intel-gw.c | 262 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 272 insertions(+)
create mode 100644 drivers/reset/reset-intel-gw.c

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index 6d5d76db55b0..6f263883eb92 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -64,6 +64,15 @@ config RESET_IMX7
help
This enables the reset controller driver for i.MX7 SoCs.

+config RESET_INTEL_GW
+ bool "Intel Reset Controller Driver"
+ depends on OF
+ select REGMAP_MMIO
+ help
+ This enables the reset controller driver for Intel Gateway SoCs.
+ Say Y to control the reset signals provided by reset controller.
+ Otherwise, say N.
+
config RESET_LANTIQ
bool "Lantiq XWAY Reset Driver" if COMPILE_TEST
default SOC_TYPE_XWAY
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 61456b8f659c..474f89ee5fd8 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
obj-$(CONFIG_RESET_BRCMSTB) += reset-brcmstb.o
obj-$(CONFIG_RESET_HSDK) += reset-hsdk.o
obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
+obj-$(CONFIG_RESET_INTEL_GW) += reset-intel-gw.o
obj-$(CONFIG_RESET_LANTIQ) += reset-lantiq.o
obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o
obj-$(CONFIG_RESET_MESON) += reset-meson.o
diff --git a/drivers/reset/reset-intel-gw.c b/drivers/reset/reset-intel-gw.c
new file mode 100644
index 000000000000..da285833cd22
--- /dev/null
+++ b/drivers/reset/reset-intel-gw.c
@@ -0,0 +1,262 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019 Intel Corporation.
+ * Lei Chuanhua <Chuanhua.lei@intel.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/init.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+
+#define RCU_RST_STAT 0x0024
+#define RCU_RST_REQ 0x0048
+
+#define REG_OFFSET GENMASK(31, 16)
+#define BIT_OFFSET GENMASK(15, 8)
+#define STAT_BIT_OFFSET GENMASK(7, 0)
+
+#define to_reset_data(x) container_of(x, struct intel_reset_data, rcdev)
+
+struct intel_reset_soc {
+ bool legacy;
+ u32 reset_cell_count;
+};
+
+struct intel_reset_data {
+ struct reset_controller_dev rcdev;
+ struct notifier_block restart_nb;
+ const struct intel_reset_soc *soc_data;
+ struct regmap *regmap;
+ struct device *dev;
+ u32 reboot_id;
+};
+
+static const struct regmap_config intel_rcu_regmap_config = {
+ .name = "intel-reset",
+ .reg_bits = 32,
+ .reg_stride = 4,
+ .val_bits = 32,
+ .fast_io = true,
+};
+
+/*
+ * Reset status register offset relative to
+ * the reset control register(X) is X + 4
+ */
+static u32 id_to_reg_and_bit_offsets(struct intel_reset_data *data,
+ unsigned long id, u32 *rst_req,
+ u32 *req_bit, u32 *stat_bit)
+{
+ *rst_req = FIELD_GET(REG_OFFSET, id);
+ *req_bit = FIELD_GET(BIT_OFFSET, id);
+
+ if (data->soc_data->legacy)
+ *stat_bit = FIELD_GET(STAT_BIT_OFFSET, id);
+ else
+ *stat_bit = *req_bit;
+
+ if (data->soc_data->legacy && *rst_req == RCU_RST_REQ)
+ return RCU_RST_STAT;
+ else
+ return *rst_req + 0x4;
+}
+
+static int intel_set_clr_bits(struct intel_reset_data *data,
+ unsigned long id, bool set, u64 timeout)
+{
+ u32 rst_req, req_bit, rst_stat, stat_bit, val;
+ int ret;
+
+ rst_stat = id_to_reg_and_bit_offsets(data, id, &rst_req,
+ &req_bit, &stat_bit);
+
+ val = set ? BIT(req_bit) : 0;
+ ret = regmap_update_bits(data->regmap, rst_req, BIT(req_bit), val);
+ if (ret)
+ return ret;
+
+ return regmap_read_poll_timeout(data->regmap, rst_stat, val,
+ set == !!(val & BIT(stat_bit)),
+ 20, timeout);
+}
+
+static int intel_assert_device(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ struct intel_reset_data *data = to_reset_data(rcdev);
+ int ret;
+
+ ret = intel_set_clr_bits(data, id, true, 200);
+ if (ret)
+ dev_err(data->dev, "Reset assert failed %d\n", ret);
+
+ return ret;
+}
+
+static int intel_deassert_device(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ struct intel_reset_data *data = to_reset_data(rcdev);
+ int ret;
+
+ ret = intel_set_clr_bits(data, id, false, 200);
+ if (ret)
+ dev_err(data->dev, "Reset deassert failed %d\n", ret);
+
+ return ret;
+}
+
+static int intel_reset_status(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ struct intel_reset_data *data = to_reset_data(rcdev);
+ u32 rst_req, req_bit, rst_stat, stat_bit, val;
+ int ret;
+
+ rst_stat = id_to_reg_and_bit_offsets(data, id, &rst_req,
+ &req_bit, &stat_bit);
+ ret = regmap_read(data->regmap, rst_stat, &val);
+ if (ret)
+ return ret;
+
+ return !!(val & BIT(stat_bit));
+}
+
+static const struct reset_control_ops intel_reset_ops = {
+ .assert = intel_assert_device,
+ .deassert = intel_deassert_device,
+ .status = intel_reset_status,
+};
+
+static int intel_reset_xlate(struct reset_controller_dev *rcdev,
+ const struct of_phandle_args *spec)
+{
+ struct intel_reset_data *data = to_reset_data(rcdev);
+ u32 id;
+
+ if (spec->args[1] > 31)
+ return -EINVAL;
+
+ id = FIELD_PREP(REG_OFFSET, spec->args[0]);
+ id |= FIELD_PREP(BIT_OFFSET, spec->args[1]);
+
+ if (data->soc_data->legacy) {
+ if (spec->args[2] > 31)
+ return -EINVAL;
+
+ id |= FIELD_PREP(STAT_BIT_OFFSET, spec->args[2]);
+ }
+
+ return id;
+}
+
+static int intel_reset_restart_handler(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct intel_reset_data *reset_data;
+
+ reset_data = container_of(nb, struct intel_reset_data, restart_nb);
+ intel_assert_device(&reset_data->rcdev, reset_data->reboot_id);
+
+ return NOTIFY_DONE;
+}
+
+static int intel_reset_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct device *dev = &pdev->dev;
+ struct intel_reset_data *data;
+ void __iomem *base;
+ u32 rb_id[3];
+ int ret;
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->soc_data = of_device_get_match_data(dev);
+ if (!data->soc_data)
+ return -ENODEV;
+
+ base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ data->regmap = devm_regmap_init_mmio(dev, base,
+ &intel_rcu_regmap_config);
+ if (IS_ERR(data->regmap)) {
+ dev_err(dev, "regmap initialization failed\n");
+ return PTR_ERR(data->regmap);
+ }
+
+ ret = device_property_read_u32_array(dev, "intel,global-reset", rb_id,
+ data->soc_data->reset_cell_count);
+ if (ret) {
+ dev_err(dev, "Failed to get global reset offset!\n");
+ return ret;
+ }
+
+ data->dev = dev;
+ data->rcdev.of_node = np;
+ data->rcdev.owner = dev->driver->owner;
+ data->rcdev.ops = &intel_reset_ops;
+ data->rcdev.of_xlate = intel_reset_xlate;
+ data->rcdev.of_reset_n_cells = data->soc_data->reset_cell_count;
+ ret = devm_reset_controller_register(&pdev->dev, &data->rcdev);
+ if (ret)
+ return ret;
+
+ data->reboot_id = FIELD_PREP(REG_OFFSET, rb_id[0]);
+ data->reboot_id |= FIELD_PREP(BIT_OFFSET, rb_id[1]);
+
+ if (data->soc_data->legacy)
+ data->reboot_id |= FIELD_PREP(STAT_BIT_OFFSET, rb_id[2]);
+
+ data->restart_nb.notifier_call = intel_reset_restart_handler;
+ data->restart_nb.priority = 128;
+ register_restart_handler(&data->restart_nb);
+
+ return 0;
+}
+
+struct intel_reset_soc xrx200_data = {
+ .legacy = true,
+ .reset_cell_count = 3,
+};
+
+struct intel_reset_soc lgm_data = {
+ .legacy = false,
+ .reset_cell_count = 2,
+};
+
+static const struct of_device_id intel_reset_match[] = {
+ { .compatible = "intel,rcu-lgm", .data = &lgm_data },
+ { .compatible = "intel,rcu-xrx200", .data = &xrx200_data },
+ {}
+};
+
+static struct platform_driver intel_reset_driver = {
+ .probe = intel_reset_probe,
+ .driver = {
+ .name = "intel-reset",
+ .of_match_table = intel_reset_match,
+ },
+};
+
+static int __init intel_reset_init(void)
+{
+ return platform_driver_register(&intel_reset_driver);
+}
+
+/*
+ * RCU is system core entity which is in Always On Domain whose clocks
+ * or resource initialization happens in system core initialization.
+ * Also, it is required for most of the platform or architecture
+ * specific devices to perform reset operation as part of initialization.
+ * So perform RCU as post core initialization.
+ */
+postcore_initcall(intel_reset_init);
--
2.11.0