clk: zx: add clock support to zx296702

It adds a clock driver for zx296702 SoC to register the clock tree to
Common Clock Framework.  All the clocks of bus topology and some the
peripheral clocks are ready with this commit. Some missing leaf clocks
for peripherals will be added later when needed.
Signed-off-by: Jun Nie <jun.nie@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Kevin Hilman <khilman@linaro.org>

drivers/clk/Makefile

@@ -72,4 +72,5 @@ obj-$(CONFIG_ARCH_OMAP2PLUS)		+= ti/
 obj-$(CONFIG_ARCH_U8500)		+= ux500/
 obj-$(CONFIG_COMMON_CLK_VERSATILE)	+= versatile/
 obj-$(CONFIG_X86)			+= x86/
+obj-$(CONFIG_ARCH_ZX)			+= zte/
 obj-$(CONFIG_ARCH_ZYNQ)			+= zynq/

drivers/clk/zte/Makefile

+obj-y := clk-pll.o
+obj-$(CONFIG_SOC_ZX296702) += clk-zx296702.o

drivers/clk/zte/clk-pll.c

+/*
+ * Copyright 2014 Linaro Ltd.
+ * Copyright (C) 2014 ZTE Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include "clk.h"
+
+#define to_clk_zx_pll(_hw) container_of(_hw, struct clk_zx_pll, hw)
+
+#define CFG0_CFG1_OFFSET 4
+#define LOCK_FLAG BIT(30)
+#define POWER_DOWN BIT(31)
+
+static int rate_to_idx(struct clk_zx_pll *zx_pll, unsigned long rate)
+{
+	const struct zx_pll_config *config = zx_pll->lookup_table;
+	int i;
+
+	for (i = 0; i < zx_pll->count; i++) {
+		if (config[i].rate > rate)
+			return i > 0 ? i - 1 : 0;
+
+		if (config[i].rate == rate)
+			return i;
+	}
+
+	return i - 1;
+}
+
+static int hw_to_idx(struct clk_zx_pll *zx_pll)
+{
+	const struct zx_pll_config *config = zx_pll->lookup_table;
+	u32 hw_cfg0, hw_cfg1;
+	int i;
+
+	hw_cfg0 = readl_relaxed(zx_pll->reg_base);
+	hw_cfg1 = readl_relaxed(zx_pll->reg_base + CFG0_CFG1_OFFSET);
+
+	/* For matching the value in lookup table */
+	hw_cfg0 &= ~LOCK_FLAG;
+	hw_cfg0 |= POWER_DOWN;
+
+	for (i = 0; i < zx_pll->count; i++) {
+		if (hw_cfg0 == config[i].cfg0 && hw_cfg1 == config[i].cfg1)
+			return i;
+	}
+
+	return -EINVAL;
+}
+
+static unsigned long zx_pll_recalc_rate(struct clk_hw *hw,
+					unsigned long parent_rate)
+{
+	struct clk_zx_pll *zx_pll = to_clk_zx_pll(hw);
+	int idx;
+
+	idx = hw_to_idx(zx_pll);
+	if (unlikely(idx == -EINVAL))
+		return 0;
+
+	return zx_pll->lookup_table[idx].rate;
+}
+
+static long zx_pll_round_rate(struct clk_hw *hw, unsigned long rate,
+			      unsigned long *prate)
+{
+	struct clk_zx_pll *zx_pll = to_clk_zx_pll(hw);
+	int idx;
+
+	idx = rate_to_idx(zx_pll, rate);
+
+	return zx_pll->lookup_table[idx].rate;
+}
+
+static int zx_pll_set_rate(struct clk_hw *hw, unsigned long rate,
+			   unsigned long parent_rate)
+{
+	/* Assume current cpu is not running on current PLL */
+	struct clk_zx_pll *zx_pll = to_clk_zx_pll(hw);
+	const struct zx_pll_config *config;
+	int idx;
+
+	idx = rate_to_idx(zx_pll, rate);
+	config = &zx_pll->lookup_table[idx];
+
+	writel_relaxed(config->cfg0, zx_pll->reg_base);
+	writel_relaxed(config->cfg1, zx_pll->reg_base + CFG0_CFG1_OFFSET);
+
+	return 0;
+}
+
+static int zx_pll_enable(struct clk_hw *hw)
+{
+	struct clk_zx_pll *zx_pll = to_clk_zx_pll(hw);
+	u32 reg;
+
+	reg = readl_relaxed(zx_pll->reg_base);
+	writel_relaxed(reg & ~POWER_DOWN, zx_pll->reg_base);
+
+	return readl_relaxed_poll_timeout(zx_pll->reg_base, reg,
+					  reg & LOCK_FLAG, 0, 100);
+}
+
+static void zx_pll_disable(struct clk_hw *hw)
+{
+	struct clk_zx_pll *zx_pll = to_clk_zx_pll(hw);
+	u32 reg;
+
+	reg = readl_relaxed(zx_pll->reg_base);
+	writel_relaxed(reg | POWER_DOWN, zx_pll->reg_base);
+}
+
+static int zx_pll_is_enabled(struct clk_hw *hw)
+{
+	struct clk_zx_pll *zx_pll = to_clk_zx_pll(hw);
+	u32 reg;
+
+	reg = readl_relaxed(zx_pll->reg_base);
+
+	return !(reg & POWER_DOWN);
+}
+
+static const struct clk_ops zx_pll_ops = {
+	.recalc_rate = zx_pll_recalc_rate,
+	.round_rate = zx_pll_round_rate,
+	.set_rate = zx_pll_set_rate,
+	.enable = zx_pll_enable,
+	.disable = zx_pll_disable,
+	.is_enabled = zx_pll_is_enabled,
+};
+
+struct clk *clk_register_zx_pll(const char *name, const char *parent_name,
+	unsigned long flags, void __iomem *reg_base,
+	const struct zx_pll_config *lookup_table, int count, spinlock_t *lock)
+{
+	struct clk_zx_pll *zx_pll;
+	struct clk *clk;
+	struct clk_init_data init;
+
+	zx_pll = kzalloc(sizeof(*zx_pll), GFP_KERNEL);
+	if (!zx_pll)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &zx_pll_ops;
+	init.flags = flags;
+	init.parent_names = parent_name ? &parent_name : NULL;
+	init.num_parents = parent_name ? 1 : 0;
+
+	zx_pll->reg_base = reg_base;
+	zx_pll->lookup_table = lookup_table;
+	zx_pll->count = count;
+	zx_pll->lock = lock;
+	zx_pll->hw.init = &init;
+
+	clk = clk_register(NULL, &zx_pll->hw);
+	if (IS_ERR(clk))
+		kfree(zx_pll);
+
+	return clk;
+}

drivers/clk/zte/clk.h

+/*
+ * Copyright 2015 Linaro Ltd.
+ * Copyright (C) 2014 ZTE Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __ZTE_CLK_H
+#define __ZTE_CLK_H
+#include <linux/clk-provider.h>
+#include <linux/spinlock.h>
+
+struct zx_pll_config {
+	unsigned long rate;
+	u32 cfg0;
+	u32 cfg1;
+};
+
+struct clk_zx_pll {
+	struct clk_hw hw;
+	void __iomem *reg_base;
+	const struct zx_pll_config *lookup_table; /* order by rate asc */
+	int count;
+	spinlock_t *lock;
+};
+
+struct clk *clk_register_zx_pll(const char *name, const char *parent_name,
+	unsigned long flags, void __iomem *reg_base,
+	const struct zx_pll_config *lookup_table, int count, spinlock_t *lock);
+#endif