[PATCH v2 2/2] reset: Reset controller driver for Intel LGM SoC

Dilip Kota
2019-08-23T05:29:07Z

Add driver for the reset controller present on Intel
Lightening Mountain (LGM) SoC 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 v2:
No changes

drivers/reset/Kconfig | 10 ++
drivers/reset/Makefile | 1 +
drivers/reset/reset-intel-syscon.c | 215 +++++++++++++++++++++++++++++++++++++
3 files changed, 226 insertions(+)
create mode 100644 drivers/reset/reset-intel-syscon.c

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index 6d5d76db55b0..e0fd14cb4cf5 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -64,6 +64,16 @@ config RESET_IMX7
help
This enables the reset controller driver for i.MX7 SoCs.

+config RESET_INTEL_SYSCON
+ bool "Intel SYSCON Reset Driver"
+ depends on HAS_IOMEM
+ select MFD_SYSCON
+ help
+ This enables the reset driver support for Intel SoC devices with
+ memory-mapped reset registers as part of a syscon device node. If
+ you wish to use the reset framework for such memory-mapped devices,
+ say Y here. 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..6d68c50c7e89 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-$(CONFIG_RESET_INTEL_SYSCON) += reset-intel-syscon.o
obj-$(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-syscon.c b/drivers/reset/reset-intel-syscon.c
new file mode 100644
index 000000000000..6377a0cac1e7
--- /dev/null
+++ b/drivers/reset/reset-intel-syscon.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019 Intel Corporation.
+ * Lei Chuanhua <Chuanhua.lei@intel.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+
+struct intel_reset_data {
+ struct reset_controller_dev rcdev;
+ struct notifier_block restart_nb;
+ struct device *dev;
+ struct regmap *regmap;
+ u32 reboot_id;
+};
+
+/* reset platform data */
+#define to_reset_data(x) container_of(x, struct intel_reset_data, rcdev)
+
+/*
+ * Reset status register offset relative to
+ * the reset control register(X) is X + 4
+ */
+static inline u32 id_to_reg_bit_and_offset(unsigned long id,
+ u32 *regbit, u32 *regoff)
+{
+ *regoff = id >> 8;
+ *regbit = id & 0x1f;
+ return *regoff + 0x4;
+}
+
+static int intel_set_clr_bits(struct intel_reset_data *data,
+ unsigned long id, bool set, u64 timeout)
+{
+ u32 regoff, regbit;
+ u32 stat_off;
+ u32 val;
+ int ret;
+
+ stat_off = id_to_reg_bit_and_offset(id, &regbit, &regoff);
+
+ val = set ? BIT(regbit) : 0;
+ ret = regmap_update_bits(data->regmap, regoff, BIT(regbit), val);
+ if (ret)
+ return ret;
+
+ return regmap_read_poll_timeout(data->regmap, stat_off, val,
+ set == !!(val & BIT(regbit)),
+ 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, 1, 200);
+ if (ret)
+ dev_err(data->dev, "Failed to set reset assert bit %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, 0, 200);
+ if (ret)
+ dev_err(data->dev,
+ "Failed to set reset deassert bit %d\n", ret);
+ return ret;
+}
+
+static int intel_reset_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, 1, 20000);
+ if (ret)
+ dev_err(data->dev, "Failed to reset device %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 regoff, regbit;
+ u32 stat_off;
+ u32 val;
+ int ret;
+
+ stat_off = id_to_reg_bit_and_offset(id, &regbit, &regoff);
+ ret = regmap_read(data->regmap, stat_off, &val);
+ if (ret)
+ return ret;
+
+ return !!(val & BIT(regbit));
+}
+
+static const struct reset_control_ops intel_reset_ops = {
+ .reset = intel_reset_device,
+ .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)
+{
+ u32 offset, bit;
+
+ offset = spec->args[0];
+ bit = spec->args[1];
+
+ return (offset << 8) | (bit & 0x1f);
+}
+
+static int intel_reset_restart_handler(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct intel_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)
+{
+ int ret;
+ struct device_node *np = pdev->dev.of_node;
+ struct device *dev = &pdev->dev;
+ struct intel_reset_data *data;
+ struct regmap *regmap;
+ u32 rb_id[2];
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ regmap = syscon_node_to_regmap(np);
+ if (IS_ERR(regmap)) {
+ dev_err(dev, "Failed to get reset controller regmap\n");
+ return PTR_ERR(regmap);
+ }
+
+ ret = device_property_read_u32_array(dev, "intel,global-reset",
+ rb_id, ARRAY_SIZE(rb_id));
+ if (ret) {
+ dev_err(dev, "Failed to get global reset offset!\n");
+ return ret;
+ }
+
+ data->dev = dev;
+ data->reboot_id = (rb_id[0] << 8) | rb_id[1];
+ data->regmap = regmap;
+ 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 = 2;
+
+ ret = devm_reset_controller_register(&pdev->dev, &data->rcdev);
+ if (ret)
+ return ret;
+
+ data->restart_nb.notifier_call = intel_reset_restart_handler;
+ data->restart_nb.priority = 128;
+
+ register_restart_handler(&data->restart_nb);
+
+ return ret;
+}
+
+static const struct of_device_id intel_reset_match[] = {
+ { .compatible = "intel,rcu-lgm" },
+ {}
+};
+
+static struct platform_driver intel_reset_driver = {
+ .probe = intel_reset_probe,
+ .driver = {
+ .name = "intel-reset-syscon",
+ .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