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Subject[PATCH v6 2/2] reset: intel: Add system reset controller driver
Date
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 v6:
Address review comments
Define structures xrx200_data and lgm_data as static const
Remove timer as parameter for intel_set_clr_bits()
Correct the alignments during restart_nb structure field assignments

Changes on v5:
Rebase patches on v5.5-rc1 kernel

Changes on v4:
No Change

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 3ad7817ce1f0..218571cda38d 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 cf60ce526064..a196d545b4b8 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..854238444616
--- /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)
+{
+ 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,
+ 200);
+}
+
+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);
+ 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);
+ 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;
+}
+
+static const struct intel_reset_soc xrx200_data = {
+ .legacy = true,
+ .reset_cell_count = 3,
+};
+
+static const 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
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