arm: vt8500: clk: Add Common Clock Framework support

This patch adds common clock framework support for arch-vt8500.
Support for PLL and device clocks on VT8500, WM8505 and WM8650
are included.

Signed-off-by: Tony Prisk <linux@prisktech.co.nz>
Acked-by: Mike Turquette <mturquette@linaro.org>

2 files changed, 511 insertions, 0 deletions

diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 5869ea387054..42fb17367f78 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_ARCH_SOCFPGA)	+= socfpga/
 obj-$(CONFIG_PLAT_SPEAR)	+= spear/
 obj-$(CONFIG_ARCH_U300)		+= clk-u300.o
 obj-$(CONFIG_ARCH_INTEGRATOR)	+= versatile/
+obj-$(CONFIG_ARCH_VT8500)	+= clk-vt8500.o
 
 # Chip specific
 obj-$(CONFIG_COMMON_CLK_WM831X) += clk-wm831x.o
diff --git a/drivers/clk/clk-vt8500.c b/drivers/clk/clk-vt8500.c
new file mode 100644
index 000000000000..a885600f5270
--- /dev/null
+++ b/drivers/clk/clk-vt8500.c
@@ -0,0 +1,510 @@
+/*
+ * Clock implementation for VIA/Wondermedia SoC's
+ * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/bitops.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+
+/* All clocks share the same lock as none can be changed concurrently */
+static DEFINE_SPINLOCK(_lock);
+
+struct clk_device {
+	struct clk_hw	hw;
+	void __iomem	*div_reg;
+	unsigned int	div_mask;
+	void __iomem	*en_reg;
+	int		en_bit;
+	spinlock_t	*lock;
+};
+
+/*
+ * Add new PLL_TYPE_x definitions here as required. Use the first known model
+ * to support the new type as the name.
+ * Add case statements to vtwm_pll_recalc_rate(), vtwm_pll_round_round() and
+ * vtwm_pll_set_rate() to handle the new PLL_TYPE_x
+ */
+
+#define PLL_TYPE_VT8500		0
+#define PLL_TYPE_WM8650		1
+
+struct clk_pll {
+	struct clk_hw	hw;
+	void __iomem	*reg;
+	spinlock_t	*lock;
+	int		type;
+};
+
+static void __iomem *pmc_base;
+
+#define to_clk_device(_hw) container_of(_hw, struct clk_device, hw)
+
+#define VT8500_PMC_BUSY_MASK		0x18
+
+static void vt8500_pmc_wait_busy(void)
+{
+	while (readl(pmc_base) & VT8500_PMC_BUSY_MASK)
+		cpu_relax();
+}
+
+static int vt8500_dclk_enable(struct clk_hw *hw)
+{
+	struct clk_device *cdev = to_clk_device(hw);
+	u32 en_val;
+	unsigned long flags = 0;
+
+	spin_lock_irqsave(cdev->lock, flags);
+
+	en_val = readl(cdev->en_reg);
+	en_val |= BIT(cdev->en_bit);
+	writel(en_val, cdev->en_reg);
+
+	spin_unlock_irqrestore(cdev->lock, flags);
+	return 0;
+}
+
+static void vt8500_dclk_disable(struct clk_hw *hw)
+{
+	struct clk_device *cdev = to_clk_device(hw);
+	u32 en_val;
+	unsigned long flags = 0;
+
+	spin_lock_irqsave(cdev->lock, flags);
+
+	en_val = readl(cdev->en_reg);
+	en_val &= ~BIT(cdev->en_bit);
+	writel(en_val, cdev->en_reg);
+
+	spin_unlock_irqrestore(cdev->lock, flags);
+}
+
+static int vt8500_dclk_is_enabled(struct clk_hw *hw)
+{
+	struct clk_device *cdev = to_clk_device(hw);
+	u32 en_val = (readl(cdev->en_reg) & BIT(cdev->en_bit));
+
+	return en_val ? 1 : 0;
+}
+
+static unsigned long vt8500_dclk_recalc_rate(struct clk_hw *hw,
+				unsigned long parent_rate)
+{
+	struct clk_device *cdev = to_clk_device(hw);
+	u32 div = readl(cdev->div_reg) & cdev->div_mask;
+
+	/* Special case for SDMMC devices */
+	if ((cdev->div_mask == 0x3F) && (div & BIT(5)))
+		div = 64 * (div & 0x1f);
+
+	/* div == 0 is actually the highest divisor */
+	if (div == 0)
+		div = (cdev->div_mask + 1);
+
+	return parent_rate / div;
+}
+
+static long vt8500_dclk_round_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long *prate)
+{
+	u32 divisor = *prate / rate;
+
+	return *prate / divisor;
+}
+
+static int vt8500_dclk_set_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long parent_rate)
+{
+	struct clk_device *cdev = to_clk_device(hw);
+	u32 divisor = parent_rate / rate;
+	unsigned long flags = 0;
+
+	if (divisor == cdev->div_mask + 1)
+		divisor = 0;
+
+	if (divisor > cdev->div_mask) {
+		pr_err("%s: invalid divisor for clock\n", __func__);
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(cdev->lock, flags);
+
+	vt8500_pmc_wait_busy();
+	writel(divisor, cdev->div_reg);
+	vt8500_pmc_wait_busy();
+
+	spin_lock_irqsave(cdev->lock, flags);
+
+	return 0;
+}
+
+
+static const struct clk_ops vt8500_gated_clk_ops = {
+	.enable = vt8500_dclk_enable,
+	.disable = vt8500_dclk_disable,
+	.is_enabled = vt8500_dclk_is_enabled,
+};
+
+static const struct clk_ops vt8500_divisor_clk_ops = {
+	.round_rate = vt8500_dclk_round_rate,
+	.set_rate = vt8500_dclk_set_rate,
+	.recalc_rate = vt8500_dclk_recalc_rate,
+};
+
+static const struct clk_ops vt8500_gated_divisor_clk_ops = {
+	.enable = vt8500_dclk_enable,
+	.disable = vt8500_dclk_disable,
+	.is_enabled = vt8500_dclk_is_enabled,
+	.round_rate = vt8500_dclk_round_rate,
+	.set_rate = vt8500_dclk_set_rate,
+	.recalc_rate = vt8500_dclk_recalc_rate,
+};
+
+#define CLK_INIT_GATED			BIT(0)
+#define CLK_INIT_DIVISOR		BIT(1)
+#define CLK_INIT_GATED_DIVISOR		(CLK_INIT_DIVISOR | CLK_INIT_GATED)
+
+static __init void vtwm_device_clk_init(struct device_node *node)
+{
+	u32 en_reg, div_reg;
+	struct clk *clk;
+	struct clk_device *dev_clk;
+	const char *clk_name = node->name;
+	const char *parent_name;
+	struct clk_init_data init;
+	int rc;
+	int clk_init_flags = 0;
+
+	dev_clk = kzalloc(sizeof(*dev_clk), GFP_KERNEL);
+	if (WARN_ON(!dev_clk))
+		return;
+
+	dev_clk->lock = &_lock;
+
+	rc = of_property_read_u32(node, "enable-reg", &en_reg);
+	if (!rc) {
+		dev_clk->en_reg = pmc_base + en_reg;
+		rc = of_property_read_u32(node, "enable-bit", &dev_clk->en_bit);
+		if (rc) {
+			pr_err("%s: enable-bit property required for gated clock\n",
+								__func__);
+			return;
+		}
+		clk_init_flags |= CLK_INIT_GATED;
+	}
+
+	rc = of_property_read_u32(node, "divisor-reg", &div_reg);
+	if (!rc) {
+		dev_clk->div_reg = pmc_base + div_reg;
+		/*
+		 * use 0x1f as the default mask since it covers
+		 * almost all the clocks and reduces dts properties
+		 */
+		dev_clk->div_mask = 0x1f;
+
+		of_property_read_u32(node, "divisor-mask", &dev_clk->div_mask);
+		clk_init_flags |= CLK_INIT_DIVISOR;
+	}
+
+	of_property_read_string(node, "clock-output-names", &clk_name);
+
+	switch (clk_init_flags) {
+	case CLK_INIT_GATED:
+		init.ops = &vt8500_gated_clk_ops;
+		break;
+	case CLK_INIT_DIVISOR:
+		init.ops = &vt8500_divisor_clk_ops;
+		break;
+	case CLK_INIT_GATED_DIVISOR:
+		init.ops = &vt8500_gated_divisor_clk_ops;
+		break;
+	default:
+		pr_err("%s: Invalid clock description in device tree\n",
+								__func__);
+		kfree(dev_clk);
+		return;
+	}
+
+	init.name = clk_name;
+	init.flags = 0;
+	parent_name = of_clk_get_parent_name(node, 0);
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+
+	dev_clk->hw.init = &init;
+
+	clk = clk_register(NULL, &dev_clk->hw);
+	if (WARN_ON(IS_ERR(clk))) {
+		kfree(dev_clk);
+		return;
+	}
+	rc = of_clk_add_provider(node, of_clk_src_simple_get, clk);
+	clk_register_clkdev(clk, clk_name, NULL);
+}
+
+
+/* PLL clock related functions */
+
+#define to_clk_pll(_hw) container_of(_hw, struct clk_pll, hw)
+
+/* Helper macros for PLL_VT8500 */
+#define VT8500_PLL_MUL(x)	((x & 0x1F) << 1)
+#define VT8500_PLL_DIV(x)	((x & 0x100) ? 1 : 2)
+
+#define VT8500_BITS_TO_FREQ(r, m, d)					\
+				((r / d) * m)
+
+#define VT8500_BITS_TO_VAL(m, d)					\
+				((d == 2 ? 0 : 0x100) | ((m >> 1) & 0x1F))
+
+/* Helper macros for PLL_WM8650 */
+#define WM8650_PLL_MUL(x)	(x & 0x3FF)
+#define WM8650_PLL_DIV(x)	(((x >> 10) & 7) * (1 << ((x >> 13) & 3)))
+
+#define WM8650_BITS_TO_FREQ(r, m, d1, d2)				\
+				(r * m / (d1 * (1 << d2)))
+
+#define WM8650_BITS_TO_VAL(m, d1, d2)					\
+				((d2 << 13) | (d1 << 10) | (m & 0x3FF))
+
+
+static void vt8500_find_pll_bits(unsigned long rate, unsigned long parent_rate,
+				u32 *multiplier, u32 *prediv)
+{
+	unsigned long tclk;
+
+	/* sanity check */
+	if ((rate < parent_rate * 4) || (rate > parent_rate * 62)) {
+		pr_err("%s: requested rate out of range\n", __func__);
+		*multiplier = 0;
+		*prediv = 1;
+		return;
+	}
+	if (rate <= parent_rate * 31)
+		/* use the prediv to double the resolution */
+		*prediv = 2;
+	else
+		*prediv = 1;
+
+	*multiplier = rate / (parent_rate / *prediv);
+	tclk = (parent_rate / *prediv) * *multiplier;
+
+	if (tclk != rate)
+		pr_warn("%s: requested rate %lu, found rate %lu\n", __func__,
+								rate, tclk);
+}
+
+static void wm8650_find_pll_bits(unsigned long rate, unsigned long parent_rate,
+				u32 *multiplier, u32 *divisor1, u32 *divisor2)
+{
+	u32 mul, div1, div2;
+	u32 best_mul, best_div1, best_div2;
+	unsigned long tclk, rate_err, best_err;
+
+	best_err = (unsigned long)-1;
+
+	/* Find the closest match (lower or equal to requested) */
+	for (div1 = 5; div1 >= 3; div1--)
+		for (div2 = 3; div2 >= 0; div2--)
+			for (mul = 3; mul <= 1023; mul++) {
+				tclk = parent_rate * mul / (div1 * (1 << div2));
+				if (tclk > rate)
+					continue;
+				/* error will always be +ve */
+				rate_err = rate - tclk;
+				if (rate_err == 0) {
+					*multiplier = mul;
+					*divisor1 = div1;
+					*divisor2 = div2;
+					return;
+				}
+
+				if (rate_err < best_err) {
+					best_err = rate_err;
+					best_mul = mul;
+					best_div1 = div1;
+					best_div2 = div2;
+				}
+			}
+
+	/* if we got here, it wasn't an exact match */
+	pr_warn("%s: requested rate %lu, found rate %lu\n", __func__, rate,
+							rate - best_err);
+	*multiplier = mul;
+	*divisor1 = div1;
+	*divisor2 = div2;
+}
+
+static int vtwm_pll_set_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long parent_rate)
+{
+	struct clk_pll *pll = to_clk_pll(hw);
+	u32 mul, div1, div2;
+	u32 pll_val;
+	unsigned long flags = 0;
+
+	/* sanity check */
+
+	switch (pll->type) {
+	case PLL_TYPE_VT8500:
+		vt8500_find_pll_bits(rate, parent_rate, &mul, &div1);
+		pll_val = VT8500_BITS_TO_VAL(mul, div1);
+		break;
+	case PLL_TYPE_WM8650:
+		wm8650_find_pll_bits(rate, parent_rate, &mul, &div1, &div2);
+		pll_val = WM8650_BITS_TO_VAL(mul, div1, div2);
+		break;
+	default:
+		pr_err("%s: invalid pll type\n", __func__);
+		return 0;
+	}
+
+	spin_lock_irqsave(pll->lock, flags);
+
+	vt8500_pmc_wait_busy();
+	writel(pll_val, pll->reg);
+	vt8500_pmc_wait_busy();
+
+	spin_unlock_irqrestore(pll->lock, flags);
+
+	return 0;
+}
+
+static long vtwm_pll_round_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long *prate)
+{
+	struct clk_pll *pll = to_clk_pll(hw);
+	u32 mul, div1, div2;
+	long round_rate;
+
+	switch (pll->type) {
+	case PLL_TYPE_VT8500:
+		vt8500_find_pll_bits(rate, *prate, &mul, &div1);
+		round_rate = VT8500_BITS_TO_FREQ(*prate, mul, div1);
+		break;
+	case PLL_TYPE_WM8650:
+		wm8650_find_pll_bits(rate, *prate, &mul, &div1, &div2);
+		round_rate = WM8650_BITS_TO_FREQ(*prate, mul, div1, div2);
+		break;
+	default:
+		round_rate = 0;
+	}
+
+	return round_rate;
+}
+
+static unsigned long vtwm_pll_recalc_rate(struct clk_hw *hw,
+				unsigned long parent_rate)
+{
+	struct clk_pll *pll = to_clk_pll(hw);
+	u32 pll_val = readl(pll->reg);
+	unsigned long pll_freq;
+
+	switch (pll->type) {
+	case PLL_TYPE_VT8500:
+		pll_freq = parent_rate * VT8500_PLL_MUL(pll_val);
+		pll_freq /= VT8500_PLL_DIV(pll_val);
+		break;
+	case PLL_TYPE_WM8650:
+		pll_freq = parent_rate * WM8650_PLL_MUL(pll_val);
+		pll_freq /= WM8650_PLL_DIV(pll_val);
+		break;
+	default:
+		pll_freq = 0;
+	}
+
+	return pll_freq;
+}
+
+const struct clk_ops vtwm_pll_ops = {
+	.round_rate = vtwm_pll_round_rate,
+	.set_rate = vtwm_pll_set_rate,
+	.recalc_rate = vtwm_pll_recalc_rate,
+};
+
+static __init void vtwm_pll_clk_init(struct device_node *node, int pll_type)
+{
+	u32 reg;
+	struct clk *clk;
+	struct clk_pll *pll_clk;
+	const char *clk_name = node->name;
+	const char *parent_name;
+	struct clk_init_data init;
+	int rc;
+
+	rc = of_property_read_u32(node, "reg", &reg);
+	if (WARN_ON(rc))
+		return;
+
+	pll_clk = kzalloc(sizeof(*pll_clk), GFP_KERNEL);
+	if (WARN_ON(!pll_clk))
+		return;
+
+	pll_clk->reg = pmc_base + reg;
+	pll_clk->lock = &_lock;
+	pll_clk->type = pll_type;
+
+	of_property_read_string(node, "clock-output-names", &clk_name);
+
+	init.name = clk_name;
+	init.ops = &vtwm_pll_ops;
+	init.flags = 0;
+	parent_name = of_clk_get_parent_name(node, 0);
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+
+	pll_clk->hw.init = &init;
+
+	clk = clk_register(NULL, &pll_clk->hw);
+	if (WARN_ON(IS_ERR(clk))) {
+		kfree(pll_clk);
+		return;
+	}
+	rc = of_clk_add_provider(node, of_clk_src_simple_get, clk);
+	clk_register_clkdev(clk, clk_name, NULL);
+}
+
+
+/* Wrappers for initialization functions */
+
+static void __init vt8500_pll_init(struct device_node *node)
+{
+	vtwm_pll_clk_init(node, PLL_TYPE_VT8500);
+}
+
+static void __init wm8650_pll_init(struct device_node *node)
+{
+	vtwm_pll_clk_init(node, PLL_TYPE_WM8650);
+}
+
+static const __initconst struct of_device_id clk_match[] = {
+	{ .compatible = "fixed-clock", .data = of_fixed_clk_setup, },
+	{ .compatible = "via,vt8500-pll-clock", .data = vt8500_pll_init, },
+	{ .compatible = "wm,wm8650-pll-clock", .data = wm8650_pll_init, },
+	{ .compatible = "via,vt8500-device-clock",
+					.data = vtwm_device_clk_init, },
+	{ /* sentinel */ }
+};
+
+void __init vtwm_clk_init(void __iomem *base)
+{
+	if (!base)
+		return;
+
+	pmc_base = base;
+
+	of_clk_init(clk_match);
+}