clk: sunxi: add PRCM (Power/Reset/Clock Management) clks support

The PRCM (Power/Reset/Clock Management) unit provides several clock
devices:
- AR100 clk: used to clock the Power Management co-processor
- AHB0 clk: used to clock the AHB0 bus
- APB0 clk and gates: used to clk peripherals connected to the APB0 bus

Add support for these clks in a separate driver so that they can be probed
as platform devices instead of registered during early init.
This is needed to be able to probe PRCM MFD subdevices.

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Emilio López <emilio@elopez.com.ar>

drivers/clk/sunxi/Makefile

@@ -5,3 +5,5 @@
 obj-y += clk-sunxi.o clk-factors.o
 obj-y += clk-a10-hosc.o
 obj-y += clk-a20-gmac.o
+
+obj-$(CONFIG_MFD_SUN6I_PRCM) += clk-sun6i-ar100.o clk-sun6i-apb0.o clk-sun6i-apb0-gates.o

drivers/clk/sunxi/clk-sun6i-apb0-gates.c

@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2014 Free Electrons
+ *
+ * License Terms: GNU General Public License v2
+ * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
+ *
+ * Allwinner A31 APB0 clock gates driver
+ *
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#define SUN6I_APB0_GATES_MAX_SIZE	32
+
+static int sun6i_a31_apb0_gates_clk_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct clk_onecell_data *clk_data;
+	const char *clk_parent;
+	const char *clk_name;
+	struct resource *r;
+	void __iomem *reg;
+	int gate_id;
+	int ngates;
+	int i;
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	reg = devm_ioremap_resource(&pdev->dev, r);
+	if (!reg)
+		return PTR_ERR(reg);
+
+	clk_parent = of_clk_get_parent_name(np, 0);
+	if (!clk_parent)
+		return -EINVAL;
+
+	ngates = of_property_count_strings(np, "clock-output-names");
+	if (ngates < 0)
+		return ngates;
+
+	if (!ngates || ngates > SUN6I_APB0_GATES_MAX_SIZE)
+		return -EINVAL;
+
+	clk_data = devm_kzalloc(&pdev->dev, sizeof(struct clk_onecell_data),
+				GFP_KERNEL);
+	if (!clk_data)
+		return -ENOMEM;
+
+	clk_data->clks = devm_kzalloc(&pdev->dev,
+				      SUN6I_APB0_GATES_MAX_SIZE *
+				      sizeof(struct clk *),
+				      GFP_KERNEL);
+	if (!clk_data->clks)
+		return -ENOMEM;
+
+	for (i = 0; i < ngates; i++) {
+		of_property_read_string_index(np, "clock-output-names",
+					      i, &clk_name);
+
+		gate_id = i;
+		of_property_read_u32_index(np, "clock-indices", i, &gate_id);
+
+		WARN_ON(gate_id >= SUN6I_APB0_GATES_MAX_SIZE);
+		if (gate_id >= SUN6I_APB0_GATES_MAX_SIZE)
+			continue;
+
+		clk_data->clks[gate_id] = clk_register_gate(&pdev->dev,
+							    clk_name,
+							    clk_parent, 0,
+							    reg, gate_id,
+							    0, NULL);
+		WARN_ON(IS_ERR(clk_data->clks[gate_id]));
+	}
+
+	clk_data->clk_num = ngates;
+
+	return of_clk_add_provider(np, of_clk_src_onecell_get, clk_data);
+}
+
+const struct of_device_id sun6i_a31_apb0_gates_clk_dt_ids[] = {
+	{ .compatible = "allwinner,sun6i-a31-apb0-gates-clk" },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver sun6i_a31_apb0_gates_clk_driver = {
+	.driver = {
+		.name = "sun6i-a31-apb0-gates-clk",
+		.owner = THIS_MODULE,
+		.of_match_table = sun6i_a31_apb0_gates_clk_dt_ids,
+	},
+	.probe = sun6i_a31_apb0_gates_clk_probe,
+};
+module_platform_driver(sun6i_a31_apb0_gates_clk_driver);
+
+MODULE_AUTHOR("Boris BREZILLON <boris.brezillon@free-electrons.com>");
+MODULE_DESCRIPTION("Allwinner A31 APB0 gate clocks driver");
+MODULE_LICENSE("GPL v2");

drivers/clk/sunxi/clk-sun6i-apb0.c

@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2014 Free Electrons
+ *
+ * License Terms: GNU General Public License v2
+ * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
+ *
+ * Allwinner A31 APB0 clock driver
+ *
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+/*
+ * The APB0 clk has a configurable divisor.
+ *
+ * We must use a clk_div_table and not a regular power of 2
+ * divisor here, because the first 2 values divide the clock
+ * by 2.
+ */
+static const struct clk_div_table sun6i_a31_apb0_divs[] = {
+	{ .val = 0, .div = 2, },
+	{ .val = 1, .div = 2, },
+	{ .val = 2, .div = 4, },
+	{ .val = 3, .div = 8, },
+	{ /* sentinel */ },
+};
+
+static int sun6i_a31_apb0_clk_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	const char *clk_name = np->name;
+	const char *clk_parent;
+	struct resource *r;
+	void __iomem *reg;
+	struct clk *clk;
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	reg = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(reg))
+		return PTR_ERR(reg);
+
+	clk_parent = of_clk_get_parent_name(np, 0);
+	if (!clk_parent)
+		return -EINVAL;
+
+	of_property_read_string(np, "clock-output-names", &clk_name);
+
+	clk = clk_register_divider_table(&pdev->dev, clk_name, clk_parent,
+					 0, reg, 0, 2, 0, sun6i_a31_apb0_divs,
+					 NULL);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	return of_clk_add_provider(np, of_clk_src_simple_get, clk);
+}
+
+const struct of_device_id sun6i_a31_apb0_clk_dt_ids[] = {
+	{ .compatible = "allwinner,sun6i-a31-apb0-clk" },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver sun6i_a31_apb0_clk_driver = {
+	.driver = {
+		.name = "sun6i-a31-apb0-clk",
+		.owner = THIS_MODULE,
+		.of_match_table = sun6i_a31_apb0_clk_dt_ids,
+	},
+	.probe = sun6i_a31_apb0_clk_probe,
+};
+module_platform_driver(sun6i_a31_apb0_clk_driver);
+
+MODULE_AUTHOR("Boris BREZILLON <boris.brezillon@free-electrons.com>");
+MODULE_DESCRIPTION("Allwinner A31 APB0 clock Driver");
+MODULE_LICENSE("GPL v2");

drivers/clk/sunxi/clk-sun6i-ar100.c

@@ -0,0 +1,233 @@
+/*
+ * Copyright (C) 2014 Free Electrons
+ *
+ * License Terms: GNU General Public License v2
+ * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
+ *
+ * Allwinner A31 AR100 clock driver
+ *
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#define SUN6I_AR100_MAX_PARENTS		4
+#define SUN6I_AR100_SHIFT_MASK		0x3
+#define SUN6I_AR100_SHIFT_MAX		SUN6I_AR100_SHIFT_MASK
+#define SUN6I_AR100_SHIFT_SHIFT		4
+#define SUN6I_AR100_DIV_MASK		0x1f
+#define SUN6I_AR100_DIV_MAX		(SUN6I_AR100_DIV_MASK + 1)
+#define SUN6I_AR100_DIV_SHIFT		8
+#define SUN6I_AR100_MUX_MASK		0x3
+#define SUN6I_AR100_MUX_SHIFT		16
+
+struct ar100_clk {
+	struct clk_hw hw;
+	void __iomem *reg;
+};
+
+static inline struct ar100_clk *to_ar100_clk(struct clk_hw *hw)
+{
+	return container_of(hw, struct ar100_clk, hw);
+}
+
+static unsigned long ar100_recalc_rate(struct clk_hw *hw,
+				       unsigned long parent_rate)
+{
+	struct ar100_clk *clk = to_ar100_clk(hw);
+	u32 val = readl(clk->reg);
+	int shift = (val >> SUN6I_AR100_SHIFT_SHIFT) & SUN6I_AR100_SHIFT_MASK;
+	int div = (val >> SUN6I_AR100_DIV_SHIFT) & SUN6I_AR100_DIV_MASK;
+
+	return (parent_rate >> shift) / (div + 1);
+}
+
+static long ar100_determine_rate(struct clk_hw *hw, unsigned long rate,
+				 unsigned long *best_parent_rate,
+				 struct clk **best_parent_clk)
+{
+	int nparents = __clk_get_num_parents(hw->clk);
+	long best_rate = -EINVAL;
+	int i;
+
+	*best_parent_clk = NULL;
+
+	for (i = 0; i < nparents; i++) {
+		unsigned long parent_rate;
+		unsigned long tmp_rate;
+		struct clk *parent;
+		unsigned long div;
+		int shift;
+
+		parent = clk_get_parent_by_index(hw->clk, i);
+		parent_rate = __clk_get_rate(parent);
+		div = DIV_ROUND_UP(parent_rate, rate);
+
+		/*
+		 * The AR100 clk contains 2 divisors:
+		 * - one power of 2 divisor
+		 * - one regular divisor
+		 *
+		 * First check if we can safely shift (or divide by a power
+		 * of 2) without losing precision on the requested rate.
+		 */
+		shift = ffs(div) - 1;
+		if (shift > SUN6I_AR100_SHIFT_MAX)
+			shift = SUN6I_AR100_SHIFT_MAX;
+
+		div >>= shift;
+
+		/*
+		 * Then if the divisor is still bigger than what the HW
+		 * actually supports, use a bigger shift (or power of 2
+		 * divider) value and accept to lose some precision.
+		 */
+		while (div > SUN6I_AR100_DIV_MAX) {
+			shift++;
+			div >>= 1;
+			if (shift > SUN6I_AR100_SHIFT_MAX)
+				break;
+		}
+
+		/*
+		 * If the shift value (or power of 2 divider) is bigger
+		 * than what the HW actually support, skip this parent.
+		 */
+		if (shift > SUN6I_AR100_SHIFT_MAX)
+			continue;
+
+		tmp_rate = (parent_rate >> shift) / div;
+		if (!*best_parent_clk || tmp_rate > best_rate) {
+			*best_parent_clk = parent;
+			*best_parent_rate = parent_rate;
+			best_rate = tmp_rate;
+		}
+	}
+
+	return best_rate;
+}
+
+static int ar100_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct ar100_clk *clk = to_ar100_clk(hw);
+	u32 val = readl(clk->reg);
+
+	if (index >= SUN6I_AR100_MAX_PARENTS)
+		return -EINVAL;
+
+	val &= ~(SUN6I_AR100_MUX_MASK << SUN6I_AR100_MUX_SHIFT);
+	val |= (index << SUN6I_AR100_MUX_SHIFT);
+	writel(val, clk->reg);
+
+	return 0;
+}
+
+static u8 ar100_get_parent(struct clk_hw *hw)
+{
+	struct ar100_clk *clk = to_ar100_clk(hw);
+	return (readl(clk->reg) >> SUN6I_AR100_MUX_SHIFT) &
+	       SUN6I_AR100_MUX_MASK;
+}
+
+static int ar100_set_rate(struct clk_hw *hw, unsigned long rate,
+			  unsigned long parent_rate)
+{
+	unsigned long div = parent_rate / rate;
+	struct ar100_clk *clk = to_ar100_clk(hw);
+	u32 val = readl(clk->reg);
+	int shift;
+
+	if (parent_rate % rate)
+		return -EINVAL;
+
+	shift = ffs(div) - 1;
+	if (shift > SUN6I_AR100_SHIFT_MAX)
+		shift = SUN6I_AR100_SHIFT_MAX;
+
+	div >>= shift;
+
+	if (div > SUN6I_AR100_DIV_MAX)
+		return -EINVAL;
+
+	val &= ~((SUN6I_AR100_SHIFT_MASK << SUN6I_AR100_SHIFT_SHIFT) |
+		 (SUN6I_AR100_DIV_MASK << SUN6I_AR100_DIV_SHIFT));
+	val |= (shift << SUN6I_AR100_SHIFT_SHIFT) |
+	       (div << SUN6I_AR100_DIV_SHIFT);
+	writel(val, clk->reg);
+
+	return 0;
+}
+
+struct clk_ops ar100_ops = {
+	.recalc_rate = ar100_recalc_rate,
+	.determine_rate = ar100_determine_rate,
+	.set_parent = ar100_set_parent,
+	.get_parent = ar100_get_parent,
+	.set_rate = ar100_set_rate,
+};
+
+static int sun6i_a31_ar100_clk_probe(struct platform_device *pdev)
+{
+	const char *parents[SUN6I_AR100_MAX_PARENTS];
+	struct device_node *np = pdev->dev.of_node;
+	const char *clk_name = np->name;
+	struct clk_init_data init;
+	struct ar100_clk *ar100;
+	struct resource *r;
+	struct clk *clk;
+	int nparents;
+	int i;
+
+	ar100 = devm_kzalloc(&pdev->dev, sizeof(*ar100), GFP_KERNEL);
+	if (!ar100)
+		return -ENOMEM;
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	ar100->reg = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(ar100->reg))
+		return PTR_ERR(ar100->reg);
+
+	nparents = of_clk_get_parent_count(np);
+	if (nparents > SUN6I_AR100_MAX_PARENTS)
+		nparents = SUN6I_AR100_MAX_PARENTS;
+
+	for (i = 0; i < nparents; i++)
+		parents[i] = of_clk_get_parent_name(np, i);
+
+	of_property_read_string(np, "clock-output-names", &clk_name);
+
+	init.name = clk_name;
+	init.ops = &ar100_ops;
+	init.parent_names = parents;
+	init.num_parents = nparents;
+	init.flags = 0;
+
+	ar100->hw.init = &init;
+
+	clk = clk_register(&pdev->dev, &ar100->hw);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	return of_clk_add_provider(np, of_clk_src_simple_get, clk);
+}
+
+const struct of_device_id sun6i_a31_ar100_clk_dt_ids[] = {
+	{ .compatible = "allwinner,sun6i-a31-ar100-clk" },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver sun6i_a31_ar100_clk_driver = {
+	.driver = {
+		.name = "sun6i-a31-ar100-clk",
+		.owner = THIS_MODULE,
+		.of_match_table = sun6i_a31_ar100_clk_dt_ids,
+	},
+	.probe = sun6i_a31_ar100_clk_probe,
+};
+module_platform_driver(sun6i_a31_ar100_clk_driver);
+
+MODULE_AUTHOR("Boris BREZILLON <boris.brezillon@free-electrons.com>");
+MODULE_DESCRIPTION("Allwinner A31 AR100 clock Driver");
+MODULE_LICENSE("GPL v2");