[PATCHv3,02/10] soc: ti: add initial PRM driver with reset control support

diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig
index fdb6743760a2..ad08d470a2ca 100644
--- a/arch/arm/mach-omap2/Kconfig
+++ b/arch/arm/mach-omap2/Kconfig
@@ -109,6 +109,7 @@  config ARCH_OMAP2PLUS
 	select TI_SYSC
 	select OMAP_IRQCHIP
 	select CLKSRC_TI_32K
+	select ARCH_HAS_RESET_CONTROLLER
 	help
 	  Systems based on OMAP2, OMAP3, OMAP4 or OMAP5
 
diff --git a/drivers/soc/ti/Makefile b/drivers/soc/ti/Makefile
index b3868d392d4f..788b5cd1e180 100644
--- a/drivers/soc/ti/Makefile
+++ b/drivers/soc/ti/Makefile
@@ -6,6 +6,7 @@  obj-$(CONFIG_KEYSTONE_NAVIGATOR_QMSS)	+= knav_qmss.o
 knav_qmss-y := knav_qmss_queue.o knav_qmss_acc.o
 obj-$(CONFIG_KEYSTONE_NAVIGATOR_DMA)	+= knav_dma.o
 obj-$(CONFIG_AMX3_PM)			+= pm33xx.o
+obj-$(CONFIG_ARCH_OMAP2PLUS)		+= omap_prm.o
 obj-$(CONFIG_WKUP_M3_IPC)		+= wkup_m3_ipc.o
 obj-$(CONFIG_TI_SCI_PM_DOMAINS)		+= ti_sci_pm_domains.o
 obj-$(CONFIG_TI_SCI_INTA_MSI_DOMAIN)	+= ti_sci_inta_msi.o
diff --git a/drivers/soc/ti/omap_prm.c b/drivers/soc/ti/omap_prm.c
new file mode 100644
index 000000000000..ab0b66ad715d
--- /dev/null
+++ b/drivers/soc/ti/omap_prm.c
@@ -0,0 +1,259 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * OMAP2+ PRM driver
+ *
+ * Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
+ *	Tero Kristo <t-kristo@ti.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/delay.h>
+
+struct omap_rst_map {
+	s8 rst;
+	s8 st;
+};
+
+struct omap_prm_data {
+	u32 base;
+	const char *name;
+	u16 rstctrl;
+	u16 rstst;
+	const struct omap_rst_map *rstmap;
+	u8 flags;
+};
+
+struct omap_prm {
+	const struct omap_prm_data *data;
+	void __iomem *base;
+};
+
+struct omap_reset_data {
+	struct reset_controller_dev rcdev;
+	struct omap_prm *prm;
+	u32 mask;
+	spinlock_t lock; /* Protect register writes */
+};
+
+#define to_omap_reset_data(p) container_of((p), struct omap_reset_data, rcdev)
+
+#define OMAP_MAX_RESETS		8
+#define OMAP_RESET_MAX_WAIT	10000
+
+#define OMAP_PRM_HAS_RSTCTRL	BIT(0)
+#define OMAP_PRM_HAS_RSTST	BIT(1)
+
+#define OMAP_PRM_HAS_RESETS	(OMAP_PRM_HAS_RSTCTRL | OMAP_PRM_HAS_RSTST)
+
+static const struct of_device_id omap_prm_id_table[] = {
+	{ },
+};
+
+static bool _is_valid_reset(struct omap_reset_data *reset, unsigned long id)
+{
+	if (reset->mask & BIT(id))
+		return true;
+
+	return false;
+}
+
+static int omap_reset_get_st_bit(struct omap_reset_data *reset,
+				 unsigned long id)
+{
+	const struct omap_rst_map *map = reset->prm->data->rstmap;
+
+	while (map->rst >= 0) {
+		if (map->rst == id)
+			return map->st;
+
+		map++;
+	}
+
+	return id;
+}
+
+static int omap_reset_status(struct reset_controller_dev *rcdev,
+			     unsigned long id)
+{
+	struct omap_reset_data *reset = to_omap_reset_data(rcdev);
+	u32 v;
+	int st_bit = omap_reset_get_st_bit(reset, id);
+	bool has_rstst = reset->prm->data->rstst ||
+		(reset->prm->data->flags & OMAP_PRM_HAS_RSTST);
+
+	/* Check if we have rstst */
+	if (!has_rstst)
+		return -ENOTSUPP;
+
+	/* Check if hw reset line is asserted */
+	v = readl_relaxed(reset->prm->base + reset->prm->data->rstctrl);
+	if (v & BIT(id))
+		return 1;
+
+	/*
+	 * Check reset status, high value means reset sequence has been
+	 * completed successfully so we can return 0 here (reset deasserted)
+	 */
+	v = readl_relaxed(reset->prm->base + reset->prm->data->rstst);
+	v >>= st_bit;
+	v &= 1;
+
+	return !v;
+}
+
+static int omap_reset_assert(struct reset_controller_dev *rcdev,
+			     unsigned long id)
+{
+	struct omap_reset_data *reset = to_omap_reset_data(rcdev);
+	u32 v;
+	unsigned long flags;
+
+	/* assert the reset control line */
+	spin_lock_irqsave(&reset->lock, flags);
+	v = readl_relaxed(reset->prm->base + reset->prm->data->rstctrl);
+	v |= 1 << id;
+	writel_relaxed(v, reset->prm->base + reset->prm->data->rstctrl);
+	spin_unlock_irqrestore(&reset->lock, flags);
+
+	return 0;
+}
+
+static int omap_reset_deassert(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	struct omap_reset_data *reset = to_omap_reset_data(rcdev);
+	u32 v;
+	int st_bit;
+	bool has_rstst;
+	unsigned long flags;
+
+	has_rstst = reset->prm->data->rstst ||
+		(reset->prm->data->flags & OMAP_PRM_HAS_RSTST);
+
+	if (has_rstst) {
+		st_bit = omap_reset_get_st_bit(reset, id);
+
+		/* Clear the reset status by writing 1 to the status bit */
+		v = readl_relaxed(reset->prm->base + reset->prm->data->rstst);
+		v |= 1 << st_bit;
+		writel_relaxed(v, reset->prm->base + reset->prm->data->rstst);
+	}
+
+	/* de-assert the reset control line */
+	spin_lock_irqsave(&reset->lock, flags);
+	v = readl_relaxed(reset->prm->base + reset->prm->data->rstctrl);
+	v &= ~(1 << id);
+	writel_relaxed(v, reset->prm->base + reset->prm->data->rstctrl);
+	spin_unlock_irqrestore(&reset->lock, flags);
+
+	return 0;
+}
+
+static const struct reset_control_ops omap_reset_ops = {
+	.assert		= omap_reset_assert,
+	.deassert	= omap_reset_deassert,
+	.status		= omap_reset_status,
+};
+
+static int omap_prm_reset_xlate(struct reset_controller_dev *rcdev,
+				const struct of_phandle_args *reset_spec)
+{
+	struct omap_reset_data *reset = to_omap_reset_data(rcdev);
+
+	if (!_is_valid_reset(reset, reset_spec->args[0]))
+		return -EINVAL;
+
+	return reset_spec->args[0];
+}
+
+static int omap_prm_reset_init(struct platform_device *pdev,
+			       struct omap_prm *prm)
+{
+	struct omap_reset_data *reset;
+	const struct omap_rst_map *map;
+
+	/*
+	 * Check if we have controllable resets. If either rstctrl is non-zero
+	 * or OMAP_PRM_HAS_RSTCTRL flag is set, we have reset control register
+	 * for the domain.
+	 */
+	if (!prm->data->rstctrl && !(prm->data->flags & OMAP_PRM_HAS_RSTCTRL))
+		return 0;
+
+	map = prm->data->rstmap;
+	if (!map)
+		return -EINVAL;
+
+	reset = devm_kzalloc(&pdev->dev, sizeof(*reset), GFP_KERNEL);
+	if (!reset)
+		return -ENOMEM;
+
+	reset->rcdev.owner = THIS_MODULE;
+	reset->rcdev.ops = &omap_reset_ops;
+	reset->rcdev.of_node = pdev->dev.of_node;
+	reset->rcdev.nr_resets = OMAP_MAX_RESETS;
+	reset->rcdev.of_xlate = omap_prm_reset_xlate;
+	reset->rcdev.of_reset_n_cells = 1;
+	spin_lock_init(&reset->lock);
+
+	reset->prm = prm;
+
+	while (map->rst >= 0) {
+		reset->mask |= BIT(map->rst);
+		map++;
+	}
+
+	return devm_reset_controller_register(&pdev->dev, &reset->rcdev);
+}
+
+static int omap_prm_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	const struct omap_prm_data *data;
+	struct omap_prm *prm;
+	const struct of_device_id *match;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	match = of_match_device(omap_prm_id_table, &pdev->dev);
+	if (!match)
+		return -ENOTSUPP;
+
+	prm = devm_kzalloc(&pdev->dev, sizeof(*prm), GFP_KERNEL);
+	if (!prm)
+		return -ENOMEM;
+
+	data = match->data;
+
+	while (data->base != res->start) {
+		if (!data->base)
+			return -EINVAL;
+		data++;
+	}
+
+	prm->data = data;
+
+	prm->base = devm_ioremap_resource(&pdev->dev, res);
+	if (!prm->base)
+		return -ENOMEM;
+
+	return omap_prm_reset_init(pdev, prm);
+}
+
+static struct platform_driver omap_prm_driver = {
+	.probe = omap_prm_probe,
+	.driver = {
+		.name		= KBUILD_MODNAME,
+		.of_match_table	= omap_prm_id_table,
+	},
+};
+builtin_platform_driver(omap_prm_driver);