clk: microchip: mpfs: add reset controller

Add a reset controller to PolarFire SoC's clock driver. This reset
controller is registered as an aux device and read/write functions
exported to the drivers namespace so that the reset controller can
access the peripheral device reset register.
Reviewed-by: Daire McNamara <daire.mcnamara@microchip.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20220909123123.2699583-5-conor.dooley@microchip.com

drivers/clk/microchip/Kconfig

@@ -6,5 +6,6 @@ config COMMON_CLK_PIC32
 config MCHP_CLK_MPFS
 	bool "Clk driver for PolarFire SoC"
 	depends on (RISCV && SOC_MICROCHIP_POLARFIRE) || COMPILE_TEST
+	select AUXILIARY_BUS
 	help
 	  Supports Clock Configuration for PolarFire SoC

drivers/clk/microchip/clk-mpfs.c

@@ -3,12 +3,14 @@
  * Daire McNamara,<daire.mcnamara@microchip.com>
  * Copyright (C) 2020 Microchip Technology Inc.  All rights reserved.
  */
+#include <linux/auxiliary_bus.h>
 #include <linux/clk-provider.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <dt-bindings/clock/microchip,mpfs-clock.h>
+#include <soc/microchip/mpfs.h>
 
 /* address offset of control registers */
 #define REG_MSSPLL_REF_CR	0x08u
@@ -28,6 +30,7 @@
 #define MSSPLL_FIXED_DIV	4u
 
 struct mpfs_clock_data {
+	struct device *dev;
 	void __iomem *base;
 	void __iomem *msspll_base;
 	struct clk_hw_onecell_data hw_data;
@@ -307,10 +310,6 @@ static int mpfs_periph_clk_enable(struct clk_hw *hw)
 
 	spin_lock_irqsave(&mpfs_clk_lock, flags);
 
-	reg = readl_relaxed(base_addr + REG_SUBBLK_RESET_CR);
-	val = reg & ~(1u << periph->shift);
-	writel_relaxed(val, base_addr + REG_SUBBLK_RESET_CR);
-
 	reg = readl_relaxed(base_addr + REG_SUBBLK_CLOCK_CR);
 	val = reg | (1u << periph->shift);
 	writel_relaxed(val, base_addr + REG_SUBBLK_CLOCK_CR);
@@ -344,12 +343,9 @@ static int mpfs_periph_clk_is_enabled(struct clk_hw *hw)
 	void __iomem *base_addr = periph_hw->sys_base;
 	u32 reg;
 
-	reg = readl_relaxed(base_addr + REG_SUBBLK_RESET_CR);
-	if ((reg & (1u << periph->shift)) == 0u) {
-		reg = readl_relaxed(base_addr + REG_SUBBLK_CLOCK_CR);
-		if (reg & (1u << periph->shift))
-			return 1;
-	}
+	reg = readl_relaxed(base_addr + REG_SUBBLK_CLOCK_CR);
+	if (reg & (1u << periph->shift))
+		return 1;
 
 	return 0;
 }
@@ -445,6 +441,94 @@ static int mpfs_clk_register_periphs(struct device *dev, struct mpfs_periph_hw_c
 	return 0;
 }
 
+/*
+ * Peripheral clock resets
+ */
+
+#if IS_ENABLED(CONFIG_RESET_CONTROLLER)
+
+u32 mpfs_reset_read(struct device *dev)
+{
+	struct mpfs_clock_data *clock_data = dev_get_drvdata(dev->parent);
+
+	return readl_relaxed(clock_data->base + REG_SUBBLK_RESET_CR);
+}
+EXPORT_SYMBOL_NS_GPL(mpfs_reset_read, MCHP_CLK_MPFS);
+
+void mpfs_reset_write(struct device *dev, u32 val)
+{
+	struct mpfs_clock_data *clock_data = dev_get_drvdata(dev->parent);
+
+	writel_relaxed(val, clock_data->base + REG_SUBBLK_RESET_CR);
+}
+EXPORT_SYMBOL_NS_GPL(mpfs_reset_write, MCHP_CLK_MPFS);
+
+static void mpfs_reset_unregister_adev(void *_adev)
+{
+	struct auxiliary_device *adev = _adev;
+
+	auxiliary_device_delete(adev);
+}
+
+static void mpfs_reset_adev_release(struct device *dev)
+{
+	struct auxiliary_device *adev = to_auxiliary_dev(dev);
+
+	auxiliary_device_uninit(adev);
+
+	kfree(adev);
+}
+
+static struct auxiliary_device *mpfs_reset_adev_alloc(struct mpfs_clock_data *clk_data)
+{
+	struct auxiliary_device *adev;
+	int ret;
+
+	adev = kzalloc(sizeof(*adev), GFP_KERNEL);
+	if (!adev)
+		return ERR_PTR(-ENOMEM);
+
+	adev->name = "reset-mpfs";
+	adev->dev.parent = clk_data->dev;
+	adev->dev.release = mpfs_reset_adev_release;
+	adev->id = 666u;
+
+	ret = auxiliary_device_init(adev);
+	if (ret) {
+		kfree(adev);
+		return ERR_PTR(ret);
+	}
+
+	return adev;
+}
+
+static int mpfs_reset_controller_register(struct mpfs_clock_data *clk_data)
+{
+	struct auxiliary_device *adev;
+	int ret;
+
+	adev = mpfs_reset_adev_alloc(clk_data);
+	if (IS_ERR(adev))
+		return PTR_ERR(adev);
+
+	ret = auxiliary_device_add(adev);
+	if (ret) {
+		auxiliary_device_uninit(adev);
+		return ret;
+	}
+
+	return devm_add_action_or_reset(clk_data->dev, mpfs_reset_unregister_adev, adev);
+}
+
+#else /* !CONFIG_RESET_CONTROLLER */
+
+static int mpfs_reset_controller_register(struct mpfs_clock_data *clk_data)
+{
+	return 0;
+}
+
+#endif /* !CONFIG_RESET_CONTROLLER */
+
 static int mpfs_clk_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -469,6 +553,8 @@ static int mpfs_clk_probe(struct platform_device *pdev)
 		return PTR_ERR(clk_data->msspll_base);
 
 	clk_data->hw_data.num = num_clks;
+	clk_data->dev = dev;
+	dev_set_drvdata(dev, clk_data);
 
 	ret = mpfs_clk_register_mssplls(dev, mpfs_msspll_clks, ARRAY_SIZE(mpfs_msspll_clks),
 					clk_data);
@@ -488,14 +574,14 @@ static int mpfs_clk_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	return ret;
+	return mpfs_reset_controller_register(clk_data);
 }
 
 static const struct of_device_id mpfs_clk_of_match_table[] = {
 	{ .compatible = "microchip,mpfs-clkcfg", },
 	{}
 };
-MODULE_DEVICE_TABLE(of, mpfs_clk_match_table);
+MODULE_DEVICE_TABLE(of, mpfs_clk_of_match_table);
 
 static struct platform_driver mpfs_clk_driver = {
 	.probe = mpfs_clk_probe,

include/soc/microchip/mpfs.h

@@ -40,4 +40,12 @@ struct mpfs_sys_controller *mpfs_sys_controller_get(struct device *dev);
 
 #endif /* if IS_ENABLED(CONFIG_POLARFIRE_SOC_SYS_CTRL) */
 
+#if IS_ENABLED(CONFIG_MCHP_CLK_MPFS)
+
+u32 mpfs_reset_read(struct device *dev);
+
+void mpfs_reset_write(struct device *dev, u32 val);
+
+#endif /* if IS_ENABLED(CONFIG_MCHP_CLK_MPFS) */
+
 #endif /* __SOC_MPFS_H__ */