[PATCH 1/2] reset: add driver for lpc18xx rgu

[manabian@gmail.com (Joachim Eastwood)]

Signed-off-by: Joachim Eastwood <manabian@gmail.com>
---
 drivers/reset/Makefile        |   1 +
 drivers/reset/reset-lpc18xx.c | 260 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 261 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..9564d78ab9d2
--- /dev/null
+++ b/drivers/reset/reset-lpc18xx.c
@@ -0,0 +1,260 @@
+/*
+ * Reset driver for NXP LPC18xx/43xx Reset Generation Unit (RGU).
+ *
+ * Copyright (C) 2014 Joachim Eastwood <manabian@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/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/reset-controller.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include <asm/system_misc.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 LPC18XX_RGU_M0SUB_RST	12
+#define LPC18XX_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 cores from accidentally getting deasserting the
+ * status register must be check and bits in control register set to
+ * preserve the state.
+ */
+static void 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);
+}
+
+static int lpc18xx_rgu_reset(struct reset_controller_dev *rcdev,
+			     unsigned long id)
+{
+	struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev);
+
+	lpc18xx_rgu_setclear_reset(rcdev, id, true);
+	udelay(rc->delay_us);
+
+	return 0;
+}
+
+static int lpc18xx_rgu_assert(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	return lpc18xx_rgu_reset(rcdev, id);
+}
+
+/* Only M0 cores require explicit reset deassert */
+static int lpc18xx_rgu_deassert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	switch (id) {
+	case LPC18XX_RGU_M0SUB_RST:
+	case LPC18XX_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@gmail.com>");
+MODULE_DESCRIPTION("Reset driver for LPC18xx/43xx RGU");
+MODULE_LICENSE("GPL v2");
-- 
1.8.0