1 files changed, 329 insertions, 0 deletions
diff --git a/drivers/clk/rockchip/clk-cpu.c b/drivers/clk/rockchip/clk-cpu.c
new file mode 100644
index 000000000000..75c8c45ef728
--- /dev/null
+++ b/drivers/clk/rockchip/clk-cpu.c
@@ -0,0 +1,329 @@
+/*
+ * Copyright (c) 2014 MundoReader S.L.
+ * Author: Heiko Stuebner <heiko@sntech.de>
+ *
+ * based on clk/samsung/clk-cpu.c
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ * Author: Thomas Abraham <thomas.ab@samsung.com>
+ *
+ * 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.
+ *
+ * A CPU clock is defined as a clock supplied to a CPU or a group of CPUs.
+ * The CPU clock is typically derived from a hierarchy of clock
+ * blocks which includes mux and divider blocks. There are a number of other
+ * auxiliary clocks supplied to the CPU domain such as the debug blocks and AXI
+ * clock for CPU domain. The rates of these auxiliary clocks are related to the
+ * CPU clock rate and this relation is usually specified in the hardware manual
+ * of the SoC or supplied after the SoC characterization.
+ *
+ * The below implementation of the CPU clock allows the rate changes of the CPU
+ * clock and the corresponding rate changes of the auxillary clocks of the CPU
+ * domain. The platform clock driver provides a clock register configuration
+ * for each configurable rate which is then used to program the clock hardware
+ * registers to acheive a fast co-oridinated rate change for all the CPU domain
+ * clocks.
+ *
+ * On a rate change request for the CPU clock, the rate change is propagated
+ * upto the PLL supplying the clock to the CPU domain clock blocks. While the
+ * CPU domain PLL is reconfigured, the CPU domain clocks are driven using an
+ * alternate clock source. If required, the alternate clock source is divided
+ * down in order to keep the output clock rate within the previous OPP limits.
+ */
+
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/clk-provider.h>
+#include "clk.h"
+
+/**
+ * struct rockchip_cpuclk: information about clock supplied to a CPU core.
+ * @hw:		handle between ccf and cpu clock.
+ * @alt_parent:	alternate parent clock to use when switching the speed
+ *		of the primary parent clock.
+ * @reg_base:	base register for cpu-clock values.
+ * @clk_nb:	clock notifier registered for changes in clock speed of the
+ *		primary parent clock.
+ * @rate_count:	number of rates in the rate_table
+ * @rate_table:	pll-rates and their associated dividers
+ * @reg_data:	cpu-specific register settings
+ * @lock:	clock lock
+ */
+struct rockchip_cpuclk {
+	struct clk_hw				hw;
+
+	struct clk_mux				cpu_mux;
+	const struct clk_ops			*cpu_mux_ops;
+
+	struct clk				*alt_parent;
+	void __iomem				*reg_base;
+	struct notifier_block			clk_nb;
+	unsigned int				rate_count;
+	struct rockchip_cpuclk_rate_table	*rate_table;
+	const struct rockchip_cpuclk_reg_data	*reg_data;
+	spinlock_t				*lock;
+};
+
+#define to_rockchip_cpuclk_hw(hw) container_of(hw, struct rockchip_cpuclk, hw)
+#define to_rockchip_cpuclk_nb(nb) \
+			container_of(nb, struct rockchip_cpuclk, clk_nb)
+
+static const struct rockchip_cpuclk_rate_table *rockchip_get_cpuclk_settings(
+			    struct rockchip_cpuclk *cpuclk, unsigned long rate)
+{
+	const struct rockchip_cpuclk_rate_table *rate_table =
+							cpuclk->rate_table;
+	int i;
+
+	for (i = 0; i < cpuclk->rate_count; i++) {
+		if (rate == rate_table[i].prate)
+			return &rate_table[i];
+	}
+
+	return NULL;
+}
+
+static unsigned long rockchip_cpuclk_recalc_rate(struct clk_hw *hw,
+					unsigned long parent_rate)
+{
+	struct rockchip_cpuclk *cpuclk = to_rockchip_cpuclk_hw(hw);
+	const struct rockchip_cpuclk_reg_data *reg_data = cpuclk->reg_data;
+	u32 clksel0 = readl_relaxed(cpuclk->reg_base + reg_data->core_reg);
+
+	clksel0 >>= reg_data->div_core_shift;
+	clksel0 &= reg_data->div_core_mask;
+	return parent_rate / (clksel0 + 1);
+}
+
+static const struct clk_ops rockchip_cpuclk_ops = {
+	.recalc_rate = rockchip_cpuclk_recalc_rate,
+};
+
+static void rockchip_cpuclk_set_dividers(struct rockchip_cpuclk *cpuclk,
+				const struct rockchip_cpuclk_rate_table *rate)
+{
+	int i;
+
+	/* alternate parent is active now. set the dividers */
+	for (i = 0; i < ARRAY_SIZE(rate->divs); i++) {
+		const struct rockchip_cpuclk_clksel *clksel = &rate->divs[i];
+
+		if (!clksel->reg)
+			continue;
+
+		pr_debug("%s: setting reg 0x%x to 0x%x\n",
+			 __func__, clksel->reg, clksel->val);
+		writel(clksel->val , cpuclk->reg_base + clksel->reg);
+	}
+}
+
+static int rockchip_cpuclk_pre_rate_change(struct rockchip_cpuclk *cpuclk,
+					   struct clk_notifier_data *ndata)
+{
+	const struct rockchip_cpuclk_reg_data *reg_data = cpuclk->reg_data;
+	unsigned long alt_prate, alt_div;
+
+	alt_prate = clk_get_rate(cpuclk->alt_parent);
+
+	spin_lock(cpuclk->lock);
+
+	/*
+	 * If the old parent clock speed is less than the clock speed
+	 * of the alternate parent, then it should be ensured that at no point
+	 * the armclk speed is more than the old_rate until the dividers are
+	 * set.
+	 */
+	if (alt_prate > ndata->old_rate) {
+		/* calculate dividers */
+		alt_div =  DIV_ROUND_UP(alt_prate, ndata->old_rate) - 1;
+		if (alt_div > reg_data->div_core_mask) {
+			pr_warn("%s: limiting alt-divider %lu to %d\n",
+				__func__, alt_div, reg_data->div_core_mask);
+			alt_div = reg_data->div_core_mask;
+		}
+
+		/*
+		 * Change parents and add dividers in a single transaction.
+		 *
+		 * NOTE: we do this in a single transaction so we're never
+		 * dividing the primary parent by the extra dividers that were
+		 * needed for the alt.
+		 */
+		pr_debug("%s: setting div %lu as alt-rate %lu > old-rate %lu\n",
+			 __func__, alt_div, alt_prate, ndata->old_rate);
+
+		writel(HIWORD_UPDATE(alt_div, reg_data->div_core_mask,
+					      reg_data->div_core_shift) |
+		       HIWORD_UPDATE(1, 1, reg_data->mux_core_shift),
+		       cpuclk->reg_base + reg_data->core_reg);
+	} else {
+		/* select alternate parent */
+		writel(HIWORD_UPDATE(1, 1, reg_data->mux_core_shift),
+			cpuclk->reg_base + reg_data->core_reg);
+	}
+
+	spin_unlock(cpuclk->lock);
+	return 0;
+}
+
+static int rockchip_cpuclk_post_rate_change(struct rockchip_cpuclk *cpuclk,
+					    struct clk_notifier_data *ndata)
+{
+	const struct rockchip_cpuclk_reg_data *reg_data = cpuclk->reg_data;
+	const struct rockchip_cpuclk_rate_table *rate;
+
+	rate = rockchip_get_cpuclk_settings(cpuclk, ndata->new_rate);
+	if (!rate) {
+		pr_err("%s: Invalid rate : %lu for cpuclk\n",
+		       __func__, ndata->new_rate);
+		return -EINVAL;
+	}
+
+	spin_lock(cpuclk->lock);
+
+	if (ndata->old_rate < ndata->new_rate)
+		rockchip_cpuclk_set_dividers(cpuclk, rate);
+
+	/*
+	 * post-rate change event, re-mux to primary parent and remove dividers.
+	 *
+	 * NOTE: we do this in a single transaction so we're never dividing the
+	 * primary parent by the extra dividers that were needed for the alt.
+	 */
+
+	writel(HIWORD_UPDATE(0, reg_data->div_core_mask,
+				reg_data->div_core_shift) |
+	       HIWORD_UPDATE(0, 1, reg_data->mux_core_shift),
+	       cpuclk->reg_base + reg_data->core_reg);
+
+	if (ndata->old_rate > ndata->new_rate)
+		rockchip_cpuclk_set_dividers(cpuclk, rate);
+
+	spin_unlock(cpuclk->lock);
+	return 0;
+}
+
+/*
+ * This clock notifier is called when the frequency of the parent clock
+ * of cpuclk is to be changed. This notifier handles the setting up all
+ * the divider clocks, remux to temporary parent and handling the safe
+ * frequency levels when using temporary parent.
+ */
+static int rockchip_cpuclk_notifier_cb(struct notifier_block *nb,
+					unsigned long event, void *data)
+{
+	struct clk_notifier_data *ndata = data;
+	struct rockchip_cpuclk *cpuclk = to_rockchip_cpuclk_nb(nb);
+	int ret = 0;
+
+	pr_debug("%s: event %lu, old_rate %lu, new_rate: %lu\n",
+		 __func__, event, ndata->old_rate, ndata->new_rate);
+	if (event == PRE_RATE_CHANGE)
+		ret = rockchip_cpuclk_pre_rate_change(cpuclk, ndata);
+	else if (event == POST_RATE_CHANGE)
+		ret = rockchip_cpuclk_post_rate_change(cpuclk, ndata);
+
+	return notifier_from_errno(ret);
+}
+
+struct clk *rockchip_clk_register_cpuclk(const char *name,
+			const char **parent_names, u8 num_parents,
+			const struct rockchip_cpuclk_reg_data *reg_data,
+			const struct rockchip_cpuclk_rate_table *rates,
+			int nrates, void __iomem *reg_base, spinlock_t *lock)
+{
+	struct rockchip_cpuclk *cpuclk;
+	struct clk_init_data init;
+	struct clk *clk, *cclk;
+	int ret;
+
+	if (num_parents != 2) {
+		pr_err("%s: needs two parent clocks\n", __func__);
+		return ERR_PTR(-EINVAL);
+	}
+
+	cpuclk = kzalloc(sizeof(*cpuclk), GFP_KERNEL);
+	if (!cpuclk)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.parent_names = &parent_names[0];
+	init.num_parents = 1;
+	init.ops = &rockchip_cpuclk_ops;
+
+	/* only allow rate changes when we have a rate table */
+	init.flags = (nrates > 0) ? CLK_SET_RATE_PARENT : 0;
+
+	/* disallow automatic parent changes by ccf */
+	init.flags |= CLK_SET_RATE_NO_REPARENT;
+
+	init.flags |= CLK_GET_RATE_NOCACHE;
+
+	cpuclk->reg_base = reg_base;
+	cpuclk->lock = lock;
+	cpuclk->reg_data = reg_data;
+	cpuclk->clk_nb.notifier_call = rockchip_cpuclk_notifier_cb;
+	cpuclk->hw.init = &init;
+
+	cpuclk->alt_parent = __clk_lookup(parent_names[1]);
+	if (!cpuclk->alt_parent) {
+		pr_err("%s: could not lookup alternate parent\n",
+		       __func__);
+		ret = -EINVAL;
+		goto free_cpuclk;
+	}
+
+	ret = clk_prepare_enable(cpuclk->alt_parent);
+	if (ret) {
+		pr_err("%s: could not enable alternate parent\n",
+		       __func__);
+		goto free_cpuclk;
+	}
+
+	clk = __clk_lookup(parent_names[0]);
+	if (!clk) {
+		pr_err("%s: could not lookup parent clock %s\n",
+		       __func__, parent_names[0]);
+		ret = -EINVAL;
+		goto free_cpuclk;
+	}
+
+	ret = clk_notifier_register(clk, &cpuclk->clk_nb);
+	if (ret) {
+		pr_err("%s: failed to register clock notifier for %s\n",
+				__func__, name);
+		goto free_cpuclk;
+	}
+
+	if (nrates > 0) {
+		cpuclk->rate_count = nrates;
+		cpuclk->rate_table = kmemdup(rates,
+					     sizeof(*rates) * nrates,
+					     GFP_KERNEL);
+		if (!cpuclk->rate_table) {
+			pr_err("%s: could not allocate memory for cpuclk rates\n",
+			       __func__);
+			ret = -ENOMEM;
+			goto unregister_notifier;
+		}
+	}
+
+	cclk = clk_register(NULL, &cpuclk->hw);
+	if (IS_ERR(clk)) {
+		pr_err("%s: could not register cpuclk %s\n", __func__,	name);
+		ret = PTR_ERR(clk);
+		goto free_rate_table;
+	}
+
+	return cclk;
+
+free_rate_table:
+	kfree(cpuclk->rate_table);
+unregister_notifier:
+	clk_notifier_unregister(clk, &cpuclk->clk_nb);
+free_cpuclk:
+	kfree(cpuclk);
+	return ERR_PTR(ret);
+}