[PATCH v2 1/2] reset: add driver for lpc18xx rgu
Joachim Eastwood
manabian at gmail.com
Mon May 4 15:52:35 PDT 2015
Signed-off-by: Joachim Eastwood <manabian at gmail.com>
---
drivers/reset/Makefile | 1 +
drivers/reset/reset-lpc18xx.c | 258 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 259 insertions(+)
create mode 100644 drivers/reset/reset-lpc18xx.c
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 157d421f755b..1d41feeb2dce 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -1,4 +1,5 @@
obj-$(CONFIG_RESET_CONTROLLER) += core.o
+obj-$(CONFIG_ARCH_LPC18XX) += reset-lpc18xx.o
obj-$(CONFIG_ARCH_SOCFPGA) += reset-socfpga.o
obj-$(CONFIG_ARCH_BERLIN) += reset-berlin.o
obj-$(CONFIG_ARCH_SUNXI) += reset-sunxi.o
diff --git a/drivers/reset/reset-lpc18xx.c b/drivers/reset/reset-lpc18xx.c
new file mode 100644
index 000000000000..50318d91e0fe
--- /dev/null
+++ b/drivers/reset/reset-lpc18xx.c
@@ -0,0 +1,258 @@
+/*
+ * Reset driver for NXP LPC18xx/43xx Reset Generation Unit (RGU).
+ *
+ * Copyright (C) 2015 Joachim Eastwood <manabian at gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/reset-controller.h>
+#include <linux/spinlock.h>
+
+/* LPC18xx RGU registers */
+#define LPC18XX_RGU_CTRL0 0x100
+#define LPC18XX_RGU_CTRL1 0x104
+#define LPC18XX_RGU_ACTIVE_STATUS0 0x150
+#define LPC18XX_RGU_ACTIVE_STATUS1 0x154
+
+#define LPC18XX_RGU_RESETS_PER_REG 32
+
+/* Internal reset outputs */
+#define LPC18XX_RGU_CORE_RST 0
+#define LPC43XX_RGU_M0SUB_RST 12
+#define LPC43XX_RGU_M0APP_RST 56
+
+struct lpc18xx_rgu_data {
+ struct reset_controller_dev rcdev;
+ struct clk *clk_delay;
+ struct clk *clk_reg;
+ void __iomem *base;
+ spinlock_t lock;
+ u32 delay_us;
+};
+
+#define to_rgu_data(rcdev) container_of(rcdev, struct lpc18xx_rgu_data, rcdev)
+
+static void __iomem *rgu_base;
+
+static int lpc18xx_rgu_restart(struct notifier_block *this, unsigned long mode,
+ void *cmd)
+{
+ writel(BIT(LPC18XX_RGU_CORE_RST), rgu_base + LPC18XX_RGU_CTRL0);
+ mdelay(2000);
+
+ pr_emerg("%s: unable to restart system\n", __func__);
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block lpc18xx_rgu_restart_nb = {
+ .notifier_call = lpc18xx_rgu_restart,
+ .priority = 192,
+};
+
+/*
+ * The LPC18xx RGU has mostly self-deasserting resets except for the
+ * two reset lines going to the internal Cortex-M0 cores.
+ *
+ * To prevent the M0 core resets from accidentally getting deasserted
+ * status register must be check and bits in control register set to
+ * preserve the state.
+ */
+static int lpc18xx_rgu_setclear_reset(struct reset_controller_dev *rcdev,
+ unsigned long id, bool set)
+{
+ struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev);
+ u32 stat_offset = LPC18XX_RGU_ACTIVE_STATUS0;
+ u32 ctrl_offset = LPC18XX_RGU_CTRL0;
+ unsigned long flags;
+ u32 stat, rst_bit;
+
+ stat_offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32);
+ ctrl_offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32);
+ rst_bit = 1 << (id % LPC18XX_RGU_RESETS_PER_REG);
+
+ spin_lock_irqsave(&rc->lock, flags);
+ stat = ~readl(rc->base + stat_offset);
+ if (set)
+ writel(stat | rst_bit, rc->base + ctrl_offset);
+ else
+ writel(stat & ~rst_bit, rc->base + ctrl_offset);
+ spin_unlock_irqrestore(&rc->lock, flags);
+
+ return 0;
+}
+
+static int lpc18xx_rgu_assert(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ return lpc18xx_rgu_setclear_reset(rcdev, id, true);
+}
+
+static int lpc18xx_rgu_deassert(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ return lpc18xx_rgu_setclear_reset(rcdev, id, false);
+}
+
+/* Only M0 cores require explicit reset deassert */
+static int lpc18xx_rgu_reset(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev);
+
+ lpc18xx_rgu_assert(rcdev, id);
+ udelay(rc->delay_us);
+
+ switch (id) {
+ case LPC43XX_RGU_M0SUB_RST:
+ case LPC43XX_RGU_M0APP_RST:
+ lpc18xx_rgu_setclear_reset(rcdev, id, false);
+ }
+
+ return 0;
+}
+
+static int lpc18xx_rgu_status(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev);
+ u32 bit, offset = LPC18XX_RGU_ACTIVE_STATUS0;
+
+ offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32);
+ bit = 1 << (id % LPC18XX_RGU_RESETS_PER_REG);
+
+ return !(readl(rc->base + offset) & bit);
+}
+
+static struct reset_control_ops lpc18xx_rgu_ops = {
+ .reset = lpc18xx_rgu_reset,
+ .assert = lpc18xx_rgu_assert,
+ .deassert = lpc18xx_rgu_deassert,
+ .status = lpc18xx_rgu_status,
+};
+
+static int lpc18xx_rgu_probe(struct platform_device *pdev)
+{
+ struct lpc18xx_rgu_data *rc;
+ struct resource *res;
+ u32 fcclk, firc;
+ int ret;
+
+ rc = devm_kzalloc(&pdev->dev, sizeof(*rc), GFP_KERNEL);
+ if (!rc)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ rc->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(rc->base))
+ return PTR_ERR(rc->base);
+
+ rc->clk_reg = devm_clk_get(&pdev->dev, "reg");
+ if (IS_ERR(rc->clk_reg)) {
+ dev_err(&pdev->dev, "reg clock not found\n");
+ return PTR_ERR(rc->clk_reg);
+ }
+
+ rc->clk_delay = devm_clk_get(&pdev->dev, "delay");
+ if (IS_ERR(rc->clk_delay)) {
+ dev_err(&pdev->dev, "delay clock not found\n");
+ return PTR_ERR(rc->clk_delay);
+ }
+
+ ret = clk_prepare_enable(rc->clk_reg);
+ if (ret) {
+ dev_err(&pdev->dev, "unable to enable reg clock\n");
+ return ret;
+ }
+
+ ret = clk_prepare_enable(rc->clk_delay);
+ if (ret) {
+ dev_err(&pdev->dev, "unable to enable delay clock\n");
+ goto dis_clk_reg;
+ }
+
+ fcclk = clk_get_rate(rc->clk_reg) / USEC_PER_SEC;
+ firc = clk_get_rate(rc->clk_delay) / USEC_PER_SEC;
+ if (fcclk == 0 || firc == 0)
+ rc->delay_us = 2;
+ else
+ rc->delay_us = DIV_ROUND_UP(fcclk, firc * firc);
+
+ spin_lock_init(&rc->lock);
+
+ rc->rcdev.owner = THIS_MODULE;
+ rc->rcdev.nr_resets = 64;
+ rc->rcdev.ops = &lpc18xx_rgu_ops;
+ rc->rcdev.of_node = pdev->dev.of_node;
+
+ platform_set_drvdata(pdev, rc);
+
+ ret = reset_controller_register(&rc->rcdev);
+ if (ret) {
+ dev_err(&pdev->dev, "unable to register device\n");
+ goto dis_clks;
+ }
+
+ rgu_base = rc->base;
+ ret = register_restart_handler(&lpc18xx_rgu_restart_nb);
+ if (ret)
+ dev_warn(&pdev->dev, "failed to register restart handler\n");
+
+ return 0;
+
+dis_clks:
+ clk_disable_unprepare(rc->clk_delay);
+dis_clk_reg:
+ clk_disable_unprepare(rc->clk_reg);
+
+ return ret;
+}
+
+static int lpc18xx_rgu_remove(struct platform_device *pdev)
+{
+ struct lpc18xx_rgu_data *rc = platform_get_drvdata(pdev);
+ int ret;
+
+ ret = unregister_restart_handler(&lpc18xx_rgu_restart_nb);
+ if (ret)
+ dev_warn(&pdev->dev, "failed to unregister restart handler\n");
+
+ reset_controller_unregister(&rc->rcdev);
+
+ clk_disable_unprepare(rc->clk_delay);
+ clk_disable_unprepare(rc->clk_reg);
+
+ return 0;
+}
+
+static const struct of_device_id lpc18xx_rgu_match[] = {
+ { .compatible = "nxp,lpc1850-rgu" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, lpc18xx_rgu_match);
+
+static struct platform_driver lpc18xx_rgu_driver = {
+ .probe = lpc18xx_rgu_probe,
+ .remove = lpc18xx_rgu_remove,
+ .driver = {
+ .name = "lpc18xx-reset",
+ .of_match_table = lpc18xx_rgu_match,
+ },
+};
+module_platform_driver(lpc18xx_rgu_driver);
+
+MODULE_AUTHOR("Joachim Eastwood <manabian at gmail.com>");
+MODULE_DESCRIPTION("Reset driver for LPC18xx/43xx RGU");
+MODULE_LICENSE("GPL v2");
--
1.8.0
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