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);
+}