clk: sunxi: Add support for USB clock-register reset bits

The usb-clk register is special in that it not only contains clk gate bits,
but also has a few reset bits. This commit adds support for this by allowing
gates type sunxi clks to also register a reset controller.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Emilio López <emilio@elopez.com.ar>

drivers/clk/sunxi/clk-sunxi.c

@@ -18,6 +18,7 @@
 #include <linux/clkdev.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/reset-controller.h>
 
 #include "clk-factors.h"
 
@@ -687,6 +688,59 @@ static void __init sunxi_divider_clk_setup(struct device_node *node,
 
 
 
+/**
+ * sunxi_gates_reset... - reset bits in leaf gate clk registers handling
+ */
+
+struct gates_reset_data {
+	void __iomem			*reg;
+	spinlock_t			*lock;
+	struct reset_controller_dev	rcdev;
+};
+
+static int sunxi_gates_reset_assert(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	struct gates_reset_data *data = container_of(rcdev,
+						     struct gates_reset_data,
+						     rcdev);
+	unsigned long flags;
+	u32 reg;
+
+	spin_lock_irqsave(data->lock, flags);
+
+	reg = readl(data->reg);
+	writel(reg & ~BIT(id), data->reg);
+
+	spin_unlock_irqrestore(data->lock, flags);
+
+	return 0;
+}
+
+static int sunxi_gates_reset_deassert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct gates_reset_data *data = container_of(rcdev,
+						     struct gates_reset_data,
+						     rcdev);
+	unsigned long flags;
+	u32 reg;
+
+	spin_lock_irqsave(data->lock, flags);
+
+	reg = readl(data->reg);
+	writel(reg | BIT(id), data->reg);
+
+	spin_unlock_irqrestore(data->lock, flags);
+
+	return 0;
+}
+
+static struct reset_control_ops sunxi_gates_reset_ops = {
+	.assert		= sunxi_gates_reset_assert,
+	.deassert	= sunxi_gates_reset_deassert,
+};
+
 /**
  * sunxi_gates_clk_setup() - Setup function for leaf gates on clocks
  */
@@ -695,6 +749,7 @@ static void __init sunxi_divider_clk_setup(struct device_node *node,
 
 struct gates_data {
 	DECLARE_BITMAP(mask, SUNXI_GATES_MAX_SIZE);
+	u32 reset_mask;
 };
 
 static const struct gates_data sun4i_axi_gates_data __initconst = {
@@ -765,6 +820,7 @@ static void __init sunxi_gates_clk_setup(struct device_node *node,
 					 struct gates_data *data)
 {
 	struct clk_onecell_data *clk_data;
+	struct gates_reset_data *reset_data;
 	const char *clk_parent;
 	const char *clk_name;
 	void *reg;
@@ -808,6 +864,21 @@ static void __init sunxi_gates_clk_setup(struct device_node *node,
 	clk_data->clk_num = i;
 
 	of_clk_add_provider(node, of_clk_src_onecell_get, clk_data);
+
+	/* Register a reset controler for gates with reset bits */
+	if (data->reset_mask == 0)
+		return;
+
+	reset_data = kzalloc(sizeof(*reset_data), GFP_KERNEL);
+	if (!reset_data)
+		return;
+
+	reset_data->reg = reg;
+	reset_data->lock = &clk_lock;
+	reset_data->rcdev.nr_resets = __fls(data->reset_mask) + 1;
+	reset_data->rcdev.ops = &sunxi_gates_reset_ops;
+	reset_data->rcdev.of_node = node;
+	reset_controller_register(&reset_data->rcdev);
 }