1 files changed, 370 insertions, 0 deletions
diff --git a/drivers/clk/renesas/clk-div6.c b/drivers/clk/renesas/clk-div6.c
new file mode 100644
index 0000000000..3abd6e5400
--- /dev/null
+++ b/drivers/clk/renesas/clk-div6.c
@@ -0,0 +1,370 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * r8a7790 Common Clock Framework support
+ *
+ * Copyright (C) 2013  Renesas Solutions Corp.
+ *
+ * Contact: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/notifier.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/pm.h>
+#include <linux/slab.h>
+
+#include "clk-div6.h"
+
+#define CPG_DIV6_CKSTP		BIT(8)
+#define CPG_DIV6_DIV(d)		((d) & 0x3f)
+#define CPG_DIV6_DIV_MASK	0x3f
+
+/**
+ * struct div6_clock - CPG 6 bit divider clock
+ * @hw: handle between common and hardware-specific interfaces
+ * @reg: IO-remapped register
+ * @div: divisor value (1-64)
+ * @src_mask: Bitmask covering the register bits to select the parent clock
+ * @nb: Notifier block to save/restore clock state for system resume
+ * @parents: Array to map from valid parent clocks indices to hardware indices
+ */
+struct div6_clock {
+	struct clk_hw hw;
+	void __iomem *reg;
+	unsigned int div;
+	u32 src_mask;
+	struct notifier_block nb;
+	u8 parents[];
+};
+
+#define to_div6_clock(_hw) container_of(_hw, struct div6_clock, hw)
+
+static int cpg_div6_clock_enable(struct clk_hw *hw)
+{
+	struct div6_clock *clock = to_div6_clock(hw);
+	u32 val;
+
+	val = (readl(clock->reg) & ~(CPG_DIV6_DIV_MASK | CPG_DIV6_CKSTP))
+	    | CPG_DIV6_DIV(clock->div - 1);
+	writel(val, clock->reg);
+
+	return 0;
+}
+
+static void cpg_div6_clock_disable(struct clk_hw *hw)
+{
+	struct div6_clock *clock = to_div6_clock(hw);
+	u32 val;
+
+	val = readl(clock->reg);
+	val |= CPG_DIV6_CKSTP;
+	/*
+	 * DIV6 clocks require the divisor field to be non-zero when stopping
+	 * the clock. However, some clocks (e.g. ZB on sh73a0) fail to be
+	 * re-enabled later if the divisor field is changed when stopping the
+	 * clock
+	 */
+	if (!(val & CPG_DIV6_DIV_MASK))
+		val |= CPG_DIV6_DIV_MASK;
+	writel(val, clock->reg);
+}
+
+static int cpg_div6_clock_is_enabled(struct clk_hw *hw)
+{
+	struct div6_clock *clock = to_div6_clock(hw);
+
+	return !(readl(clock->reg) & CPG_DIV6_CKSTP);
+}
+
+static unsigned long cpg_div6_clock_recalc_rate(struct clk_hw *hw,
+						unsigned long parent_rate)
+{
+	struct div6_clock *clock = to_div6_clock(hw);
+
+	return parent_rate / clock->div;
+}
+
+static unsigned int cpg_div6_clock_calc_div(unsigned long rate,
+					    unsigned long parent_rate)
+{
+	unsigned int div;
+
+	if (!rate)
+		rate = 1;
+
+	div = DIV_ROUND_CLOSEST(parent_rate, rate);
+	return clamp(div, 1U, 64U);
+}
+
+static int cpg_div6_clock_determine_rate(struct clk_hw *hw,
+					 struct clk_rate_request *req)
+{
+	unsigned long prate, calc_rate, diff, best_rate, best_prate;
+	unsigned int num_parents = clk_hw_get_num_parents(hw);
+	struct clk_hw *parent, *best_parent = NULL;
+	unsigned int i, min_div, max_div, div;
+	unsigned long min_diff = ULONG_MAX;
+
+	for (i = 0; i < num_parents; i++) {
+		parent = clk_hw_get_parent_by_index(hw, i);
+		if (!parent)
+			continue;
+
+		prate = clk_hw_get_rate(parent);
+		if (!prate)
+			continue;
+
+		min_div = max(DIV_ROUND_UP(prate, req->max_rate), 1UL);
+		max_div = req->min_rate ? min(prate / req->min_rate, 64UL) : 64;
+		if (max_div < min_div)
+			continue;
+
+		div = cpg_div6_clock_calc_div(req->rate, prate);
+		div = clamp(div, min_div, max_div);
+		calc_rate = prate / div;
+		diff = calc_rate > req->rate ? calc_rate - req->rate
+					     : req->rate - calc_rate;
+		if (diff < min_diff) {
+			best_rate = calc_rate;
+			best_parent = parent;
+			best_prate = prate;
+			min_diff = diff;
+		}
+	}
+
+	if (!best_parent)
+		return -EINVAL;
+
+	req->best_parent_rate = best_prate;
+	req->best_parent_hw = best_parent;
+	req->rate = best_rate;
+	return 0;
+}
+
+static int cpg_div6_clock_set_rate(struct clk_hw *hw, unsigned long rate,
+				   unsigned long parent_rate)
+{
+	struct div6_clock *clock = to_div6_clock(hw);
+	unsigned int div = cpg_div6_clock_calc_div(rate, parent_rate);
+	u32 val;
+
+	clock->div = div;
+
+	val = readl(clock->reg) & ~CPG_DIV6_DIV_MASK;
+	/* Only program the new divisor if the clock isn't stopped. */
+	if (!(val & CPG_DIV6_CKSTP))
+		writel(val | CPG_DIV6_DIV(clock->div - 1), clock->reg);
+
+	return 0;
+}
+
+static u8 cpg_div6_clock_get_parent(struct clk_hw *hw)
+{
+	struct div6_clock *clock = to_div6_clock(hw);
+	unsigned int i;
+	u8 hw_index;
+
+	if (clock->src_mask == 0)
+		return 0;
+
+	hw_index = (readl(clock->reg) & clock->src_mask) >>
+		   __ffs(clock->src_mask);
+	for (i = 0; i < clk_hw_get_num_parents(hw); i++) {
+		if (clock->parents[i] == hw_index)
+			return i;
+	}
+
+	pr_err("%s: %s DIV6 clock set to invalid parent %u\n",
+	       __func__, clk_hw_get_name(hw), hw_index);
+	return 0;
+}
+
+static int cpg_div6_clock_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct div6_clock *clock = to_div6_clock(hw);
+	u32 src;
+
+	if (index >= clk_hw_get_num_parents(hw))
+		return -EINVAL;
+
+	src = clock->parents[index] << __ffs(clock->src_mask);
+	writel((readl(clock->reg) & ~clock->src_mask) | src, clock->reg);
+	return 0;
+}
+
+static const struct clk_ops cpg_div6_clock_ops = {
+	.enable = cpg_div6_clock_enable,
+	.disable = cpg_div6_clock_disable,
+	.is_enabled = cpg_div6_clock_is_enabled,
+	.get_parent = cpg_div6_clock_get_parent,
+	.set_parent = cpg_div6_clock_set_parent,
+	.recalc_rate = cpg_div6_clock_recalc_rate,
+	.determine_rate = cpg_div6_clock_determine_rate,
+	.set_rate = cpg_div6_clock_set_rate,
+};
+
+static int cpg_div6_clock_notifier_call(struct notifier_block *nb,
+					unsigned long action, void *data)
+{
+	struct div6_clock *clock = container_of(nb, struct div6_clock, nb);
+
+	switch (action) {
+	case PM_EVENT_RESUME:
+		/*
+		 * TODO: This does not yet support DIV6 clocks with multiple
+		 * parents, as the parent selection bits are not restored.
+		 * Fortunately so far such DIV6 clocks are found only on
+		 * R/SH-Mobile SoCs, while the resume functionality is only
+		 * needed on R-Car Gen3.
+		 */
+		if (__clk_get_enable_count(clock->hw.clk))
+			cpg_div6_clock_enable(&clock->hw);
+		else
+			cpg_div6_clock_disable(&clock->hw);
+		return NOTIFY_OK;
+	}
+
+	return NOTIFY_DONE;
+}
+
+/**
+ * cpg_div6_register - Register a DIV6 clock
+ * @name: Name of the DIV6 clock
+ * @num_parents: Number of parent clocks of the DIV6 clock (1, 4, or 8)
+ * @parent_names: Array containing the names of the parent clocks
+ * @reg: Mapped register used to control the DIV6 clock
+ * @notifiers: Optional notifier chain to save/restore state for system resume
+ */
+struct clk * __init cpg_div6_register(const char *name,
+				      unsigned int num_parents,
+				      const char **parent_names,
+				      void __iomem *reg,
+				      struct raw_notifier_head *notifiers)
+{
+	unsigned int valid_parents;
+	struct clk_init_data init = {};
+	struct div6_clock *clock;
+	struct clk *clk;
+	unsigned int i;
+
+	clock = kzalloc(struct_size(clock, parents, num_parents), GFP_KERNEL);
+	if (!clock)
+		return ERR_PTR(-ENOMEM);
+
+	clock->reg = reg;
+
+	/*
+	 * Read the divisor. Disabling the clock overwrites the divisor, so we
+	 * need to cache its value for the enable operation.
+	 */
+	clock->div = (readl(clock->reg) & CPG_DIV6_DIV_MASK) + 1;
+
+	switch (num_parents) {
+	case 1:
+		/* fixed parent clock */
+		clock->src_mask = 0;
+		break;
+	case 4:
+		/* clock with EXSRC bits 6-7 */
+		clock->src_mask = GENMASK(7, 6);
+		break;
+	case 8:
+		/* VCLK with EXSRC bits 12-14 */
+		clock->src_mask = GENMASK(14, 12);
+		break;
+	default:
+		pr_err("%s: invalid number of parents for DIV6 clock %s\n",
+		       __func__, name);
+		clk = ERR_PTR(-EINVAL);
+		goto free_clock;
+	}
+
+	/* Filter out invalid parents */
+	for (i = 0, valid_parents = 0; i < num_parents; i++) {
+		if (parent_names[i]) {
+			parent_names[valid_parents] = parent_names[i];
+			clock->parents[valid_parents] = i;
+			valid_parents++;
+		}
+	}
+
+	/* Register the clock. */
+	init.name = name;
+	init.ops = &cpg_div6_clock_ops;
+	init.parent_names = parent_names;
+	init.num_parents = valid_parents;
+
+	clock->hw.init = &init;
+
+	clk = clk_register(NULL, &clock->hw);
+	if (IS_ERR(clk))
+		goto free_clock;
+
+	if (notifiers) {
+		clock->nb.notifier_call = cpg_div6_clock_notifier_call;
+		raw_notifier_chain_register(notifiers, &clock->nb);
+	}
+
+	return clk;
+
+free_clock:
+	kfree(clock);
+	return clk;
+}
+
+static void __init cpg_div6_clock_init(struct device_node *np)
+{
+	unsigned int num_parents;
+	const char **parent_names;
+	const char *clk_name = np->name;
+	void __iomem *reg;
+	struct clk *clk;
+	unsigned int i;
+
+	num_parents = of_clk_get_parent_count(np);
+	if (num_parents < 1) {
+		pr_err("%s: no parent found for %pOFn DIV6 clock\n",
+		       __func__, np);
+		return;
+	}
+
+	parent_names = kmalloc_array(num_parents, sizeof(*parent_names),
+				GFP_KERNEL);
+	if (!parent_names)
+		return;
+
+	reg = of_iomap(np, 0);
+	if (reg == NULL) {
+		pr_err("%s: failed to map %pOFn DIV6 clock register\n",
+		       __func__, np);
+		goto error;
+	}
+
+	/* Parse the DT properties. */
+	of_property_read_string(np, "clock-output-names", &clk_name);
+
+	for (i = 0; i < num_parents; i++)
+		parent_names[i] = of_clk_get_parent_name(np, i);
+
+	clk = cpg_div6_register(clk_name, num_parents, parent_names, reg, NULL);
+	if (IS_ERR(clk)) {
+		pr_err("%s: failed to register %pOFn DIV6 clock (%ld)\n",
+		       __func__, np, PTR_ERR(clk));
+		goto error;
+	}
+
+	of_clk_add_provider(np, of_clk_src_simple_get, clk);
+
+	kfree(parent_names);
+	return;
+
+error:
+	if (reg)
+		iounmap(reg);
+	kfree(parent_names);
+}
+CLK_OF_DECLARE(cpg_div6_clk, "renesas,cpg-div6-clock", cpg_div6_clock_init);