reset: mpfs: add non-auxiliary bus probing

While the auxiliary bus was a nice bandaid, and meant that re-writing
the representation of the clock regions in devicetree was not required,
it has run its course. The "mss_top_sysreg" region that contains the
clock and reset regions, also contains pinctrl and an interrupt
controller, so the time has come rewrite the devicetree and probe the
reset controller from an mfd devicetree node, rather than implement
those drivers using the auxiliary bus. Wanting to avoid propagating this
naive/incorrect description of the hardware to the new pic64gx SoC is a
major motivating factor here.

Reviewed-by: Philipp Zabel <[e-mail]>
Acked-by: Philipp Zabel <[e-mail]>
Signed-off-by: Conor Dooley <[e-mail]>

drivers/clk/microchip/clk-mpfs.c

···
 	.reg_stride = 4,
 	.val_bits = 32,
 	.val_format_endian = REGMAP_ENDIAN_LITTLE,
-	.max_register = REG_SUBBLK_CLOCK_CR,
+	.max_register = REG_SUBBLK_RESET_CR,
 };
 
 /*
···
 	if (IS_ERR(clk_data->regmap))
 		return PTR_ERR(clk_data->regmap);
 
-	return mpfs_reset_controller_register(dev, clk_data->base + REG_SUBBLK_RESET_CR);
+	return mpfs_reset_controller_register(dev, clk_data->regmap);
 }
 
 static int mpfs_clk_probe(struct platform_device *pdev)

drivers/reset/Kconfig

···
 config RESET_POLARFIRE_SOC
 	bool "Microchip PolarFire SoC (MPFS) Reset Driver"
 	depends on MCHP_CLK_MPFS
+	depends on MFD_SYSCON
 	select AUXILIARY_BUS
 	default MCHP_CLK_MPFS
 	help

drivers/reset/reset-mpfs.c

···
 #include <linux/auxiliary_bus.h>
 #include <linux/delay.h>
 #include <linux/io.h>
+#include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
-#include <linux/slab.h>
+#include <linux/regmap.h>
 #include <linux/reset-controller.h>
+#include <linux/slab.h>
 #include <dt-bindings/clock/microchip,mpfs-clock.h>
 #include <soc/microchip/mpfs.h>
 
···
 #define MPFS_SLEEP_MIN_US	100
 #define MPFS_SLEEP_MAX_US	200
 
-/* block concurrent access to the soft reset register */
-static DEFINE_SPINLOCK(mpfs_reset_lock);
+#define REG_SUBBLK_RESET_CR	0x88u
 
 struct mpfs_reset {
-	void __iomem *base;
+	struct regmap *regmap;
 	struct reset_controller_dev rcdev;
 };
 
···
 static int mpfs_assert(struct reset_controller_dev *rcdev, unsigned long id)
 {
 	struct mpfs_reset *rst = to_mpfs_reset(rcdev);
-	unsigned long flags;
-	u32 reg;
 
-	spin_lock_irqsave(&mpfs_reset_lock, flags);
+	return regmap_set_bits(rst->regmap, REG_SUBBLK_RESET_CR, BIT(id));
 
-	reg = readl(rst->base);
-	reg |= BIT(id);
-	writel(reg, rst->base);
-
-	spin_unlock_irqrestore(&mpfs_reset_lock, flags);
-
-	return 0;
 }
 
 static int mpfs_deassert(struct reset_controller_dev *rcdev, unsigned long id)
 {
 	struct mpfs_reset *rst = to_mpfs_reset(rcdev);
-	unsigned long flags;
-	u32 reg;
 
-	spin_lock_irqsave(&mpfs_reset_lock, flags);
+	return regmap_clear_bits(rst->regmap, REG_SUBBLK_RESET_CR, BIT(id));
 
-	reg = readl(rst->base);
-	reg &= ~BIT(id);
-	writel(reg, rst->base);
-
-	spin_unlock_irqrestore(&mpfs_reset_lock, flags);
-
-	return 0;
 }
 
 static int mpfs_status(struct reset_controller_dev *rcdev, unsigned long id)
 {
 	struct mpfs_reset *rst = to_mpfs_reset(rcdev);
-	u32 reg = readl(rst->base);
+	u32 reg;
+
+	regmap_read(rst->regmap, REG_SUBBLK_RESET_CR, &reg);
 
 	/*
 	 * It is safe to return here as MPFS_NUM_RESETS makes sure the sign bit
···
 	return index - MPFS_PERIPH_OFFSET;
 }
 
-static int mpfs_reset_probe(struct auxiliary_device *adev,
-			    const struct auxiliary_device_id *id)
+static int mpfs_reset_mfd_probe(struct platform_device *pdev)
 {
-	struct device *dev = &adev->dev;
 	struct reset_controller_dev *rcdev;
+	struct device *dev = &pdev->dev;
 	struct mpfs_reset *rst;
 
 	rst = devm_kzalloc(dev, sizeof(*rst), GFP_KERNEL);
 	if (!rst)
 		return -ENOMEM;
 
-	rst->base = (void __iomem *)adev->dev.platform_data;
+	rcdev = &rst->rcdev;
+	rcdev->dev = dev;
+	rcdev->ops = &mpfs_reset_ops;
+
+	rcdev->of_node = pdev->dev.parent->of_node;
+	rcdev->of_reset_n_cells = 1;
+	rcdev->of_xlate = mpfs_reset_xlate;
+	rcdev->nr_resets = MPFS_NUM_RESETS;
+
+	rst->regmap = device_node_to_regmap(pdev->dev.parent->of_node);
+	if (IS_ERR(rst->regmap))
+		return dev_err_probe(dev, PTR_ERR(rst->regmap),
+				     "Failed to find syscon regmap\n");
+
+	return devm_reset_controller_register(dev, rcdev);
+}
+
+static struct platform_driver mpfs_reset_mfd_driver = {
+	.probe = mpfs_reset_mfd_probe,
+	.driver = {
+		.name = "mpfs-reset",
+	},
+};
+module_platform_driver(mpfs_reset_mfd_driver);
+
+static int mpfs_reset_adev_probe(struct auxiliary_device *adev,
+				 const struct auxiliary_device_id *id)
+{
+	struct reset_controller_dev *rcdev;
+	struct device *dev = &adev->dev;
+	struct mpfs_reset *rst;
+
+	rst = devm_kzalloc(dev, sizeof(*rst), GFP_KERNEL);
+	if (!rst)
+		return -ENOMEM;
+
+	rst->regmap = (struct regmap *)adev->dev.platform_data;
 
 	rcdev = &rst->rcdev;
 	rcdev->dev = dev;
-	rcdev->dev->parent = dev->parent;
 	rcdev->ops = &mpfs_reset_ops;
+
 	rcdev->of_node = dev->parent->of_node;
 	rcdev->of_reset_n_cells = 1;
 	rcdev->of_xlate = mpfs_reset_xlate;
···
 	return devm_reset_controller_register(dev, rcdev);
 }
 
-int mpfs_reset_controller_register(struct device *clk_dev, void __iomem *base)
+int mpfs_reset_controller_register(struct device *clk_dev, struct regmap *map)
 {
 	struct auxiliary_device *adev;
 
-	adev = devm_auxiliary_device_create(clk_dev, "reset-mpfs",
-					    (__force void *)base);
+	adev = devm_auxiliary_device_create(clk_dev, "reset-mpfs", (void *)map);
 	if (!adev)
 		return -ENODEV;
 
···
 };
 MODULE_DEVICE_TABLE(auxiliary, mpfs_reset_ids);
 
-static struct auxiliary_driver mpfs_reset_driver = {
-	.probe		= mpfs_reset_probe,
+static struct auxiliary_driver mpfs_reset_aux_driver = {
+	.probe		= mpfs_reset_adev_probe,
 	.id_table	= mpfs_reset_ids,
 };
 
-module_auxiliary_driver(mpfs_reset_driver);
+module_auxiliary_driver(mpfs_reset_aux_driver);
 
 MODULE_DESCRIPTION("Microchip PolarFire SoC Reset Driver");
 MODULE_AUTHOR("Conor Dooley <[e-mail]>");

include/soc/microchip/mpfs.h

···
 
 #include <linux/types.h>
 #include <linux/of_device.h>
+#include <linux/regmap.h>
 
 struct mpfs_sys_controller;
 
···
 
 #if IS_ENABLED(CONFIG_MCHP_CLK_MPFS)
 #if IS_ENABLED(CONFIG_RESET_POLARFIRE_SOC)
-int mpfs_reset_controller_register(struct device *clk_dev, void __iomem *base);
+int mpfs_reset_controller_register(struct device *clk_dev, struct regmap *map);
 #else
 static inline int mpfs_reset_controller_register(struct device *clk_dev, void __iomem *base) { return 0; }
 #endif /* if IS_ENABLED(CONFIG_RESET_POLARFIRE_SOC) */