clk: meson: Add support for Meson clock controller

This patchset adds the infrastructure for registering and managing the core clocks found on Amlogic MesonX SoCs. In particular: - PLLs - CPU clock - Fixed rate clocks, fixed factor clocks, ... Signed-off-by: Carlo Caione <[email protected]> Signed-off-by: Stephen Boyd <[email protected]>
kakra · Jun 6, 2015 · 7a29a86 · 7a29a86
1 parent b787f68
commit 7a29a86
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diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
@@ -55,6 +55,7 @@ ifeq ($(CONFIG_COMMON_CLK), y)
 obj-$(CONFIG_ARCH_MMP)			+= mmp/
 endif
 obj-$(CONFIG_PLAT_ORION)		+= mvebu/
+obj-$(CONFIG_ARCH_MESON)		+= meson/
 obj-$(CONFIG_ARCH_MXS)			+= mxs/
 obj-$(CONFIG_MACH_PISTACHIO)		+= pistachio/
 obj-$(CONFIG_COMMON_CLK_PXA)		+= pxa/

diff --git a/drivers/clk/meson/Makefile b/drivers/clk/meson/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for Meson specific clk
+#
+
+obj-y += clkc.o clk-pll.o clk-cpu.o
diff --git a/drivers/clk/meson/clk-cpu.c b/drivers/clk/meson/clk-cpu.c
@@ -0,0 +1,234 @@
+/*
+ * Copyright (c) 2015 Endless Mobile, Inc.
+ * Author: Carlo Caione <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * CPU clock path:
+ *
+ *                           +-[/N]-----|3|
+ *             MUX2  +--[/3]-+----------|2| MUX1
+ * [sys_pll]---|1|   |--[/2]------------|1|-|1|
+ *             | |---+------------------|0| | |----- [a5_clk]
+ *          +--|0|                          | |
+ * [xtal]---+-------------------------------|0|
+ *
+ *
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <linux/clk-provider.h>
+
+#define MESON_CPU_CLK_CNTL1		0x00
+#define MESON_CPU_CLK_CNTL		0x40
+
+#define MESON_CPU_CLK_MUX1		BIT(7)
+#define MESON_CPU_CLK_MUX2		BIT(0)
+
+#define MESON_N_WIDTH			9
+#define MESON_N_SHIFT			20
+#define MESON_SEL_WIDTH			2
+#define MESON_SEL_SHIFT			2
+
+#include "clkc.h"
+
+struct meson_clk_cpu {
+	struct notifier_block		clk_nb;
+	const struct clk_div_table	*div_table;
+	struct clk_hw			hw;
+	void __iomem			*base;
+	u16				reg_off;
+};
+#define to_meson_clk_cpu_hw(_hw) container_of(_hw, struct meson_clk_cpu, hw)
+#define to_meson_clk_cpu_nb(_nb) container_of(_nb, struct meson_clk_cpu, clk_nb)
+
+static long meson_clk_cpu_round_rate(struct clk_hw *hw, unsigned long rate,
+				     unsigned long *prate)
+{
+	struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_hw(hw);
+
+	return divider_round_rate(hw, rate, prate, clk_cpu->div_table,
+				  MESON_N_WIDTH, CLK_DIVIDER_ROUND_CLOSEST);
+}
+
+static int meson_clk_cpu_set_rate(struct clk_hw *hw, unsigned long rate,
+				  unsigned long parent_rate)
+{
+	struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_hw(hw);
+	unsigned int div, sel, N = 0;
+	u32 reg;
+
+	div = DIV_ROUND_UP(parent_rate, rate);
+
+	if (div <= 3) {
+		sel = div - 1;
+	} else {
+		sel = 3;
+		N = div / 2;
+	}
+
+	reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL1);
+	reg = PARM_SET(MESON_N_WIDTH, MESON_N_SHIFT, reg, N);
+	writel(reg, clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL1);
+
+	reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL);
+	reg = PARM_SET(MESON_SEL_WIDTH, MESON_SEL_SHIFT, reg, sel);
+	writel(reg, clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL);
+
+	return 0;
+}
+
+static unsigned long meson_clk_cpu_recalc_rate(struct clk_hw *hw,
+					       unsigned long parent_rate)
+{
+	struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_hw(hw);
+	unsigned int N, sel;
+	unsigned int div = 1;
+	u32 reg;
+
+	reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL1);
+	N = PARM_GET(MESON_N_WIDTH, MESON_N_SHIFT, reg);
+
+	reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL);
+	sel = PARM_GET(MESON_SEL_WIDTH, MESON_SEL_SHIFT, reg);
+
+	if (sel < 3)
+		div = sel + 1;
+	else
+		div = 2 * N;
+
+	return parent_rate / div;
+}
+
+static int meson_clk_cpu_pre_rate_change(struct meson_clk_cpu *clk_cpu,
+					 struct clk_notifier_data *ndata)
+{
+	u32 cpu_clk_cntl;
+
+	/* switch MUX1 to xtal */
+	cpu_clk_cntl = readl(clk_cpu->base + clk_cpu->reg_off
+				+ MESON_CPU_CLK_CNTL);
+	cpu_clk_cntl &= ~MESON_CPU_CLK_MUX1;
+	writel(cpu_clk_cntl, clk_cpu->base + clk_cpu->reg_off
+				+ MESON_CPU_CLK_CNTL);
+	udelay(100);
+
+	/* switch MUX2 to sys-pll */
+	cpu_clk_cntl |= MESON_CPU_CLK_MUX2;
+	writel(cpu_clk_cntl, clk_cpu->base + clk_cpu->reg_off
+				+ MESON_CPU_CLK_CNTL);
+
+	return 0;
+}
+
+static int meson_clk_cpu_post_rate_change(struct meson_clk_cpu *clk_cpu,
+					  struct clk_notifier_data *ndata)
+{
+	u32 cpu_clk_cntl;
+
+	/* switch MUX1 to divisors' output */
+	cpu_clk_cntl = readl(clk_cpu->base + clk_cpu->reg_off
+				+ MESON_CPU_CLK_CNTL);
+	cpu_clk_cntl |= MESON_CPU_CLK_MUX1;
+	writel(cpu_clk_cntl, clk_cpu->base + clk_cpu->reg_off
+				+ MESON_CPU_CLK_CNTL);
+	udelay(100);
+
+	return 0;
+}
+
+/*
+ * This clock notifier is called when the frequency of the of the parent
+ * PLL clock is to be changed. We use the xtal input as temporary parent
+ * while the PLL frequency is stabilized.
+ */
+static int meson_clk_cpu_notifier_cb(struct notifier_block *nb,
+				     unsigned long event, void *data)
+{
+	struct clk_notifier_data *ndata = data;
+	struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_nb(nb);
+	int ret = 0;
+
+	if (event == PRE_RATE_CHANGE)
+		ret = meson_clk_cpu_pre_rate_change(clk_cpu, ndata);
+	else if (event == POST_RATE_CHANGE)
+		ret = meson_clk_cpu_post_rate_change(clk_cpu, ndata);
+
+	return notifier_from_errno(ret);
+}
+
+static const struct clk_ops meson_clk_cpu_ops = {
+	.recalc_rate	= meson_clk_cpu_recalc_rate,
+	.round_rate	= meson_clk_cpu_round_rate,
+	.set_rate	= meson_clk_cpu_set_rate,
+};
+
+struct clk *meson_clk_register_cpu(const struct clk_conf *clk_conf,
+				   void __iomem *reg_base,
+				   spinlock_t *lock)
+{
+	struct clk *clk;
+	struct clk *pclk;
+	struct meson_clk_cpu *clk_cpu;
+	struct clk_init_data init;
+	int ret;
+
+	clk_cpu = kzalloc(sizeof(*clk_cpu), GFP_KERNEL);
+	if (!clk_cpu)
+		return ERR_PTR(-ENOMEM);
+
+	clk_cpu->base = reg_base;
+	clk_cpu->reg_off = clk_conf->reg_off;
+	clk_cpu->div_table = clk_conf->conf.div_table;
+	clk_cpu->clk_nb.notifier_call = meson_clk_cpu_notifier_cb;
+
+	init.name = clk_conf->clk_name;
+	init.ops = &meson_clk_cpu_ops;
+	init.flags = clk_conf->flags | CLK_GET_RATE_NOCACHE;
+	init.flags |= CLK_SET_RATE_PARENT;
+	init.parent_names = clk_conf->clks_parent;
+	init.num_parents = 1;
+
+	clk_cpu->hw.init = &init;
+
+	pclk = __clk_lookup(clk_conf->clks_parent[0]);
+	if (!pclk) {
+		pr_err("%s: could not lookup parent clock %s\n",
+				__func__, clk_conf->clks_parent[0]);
+		return ERR_PTR(-EINVAL);
+	}
+
+	ret = clk_notifier_register(pclk, &clk_cpu->clk_nb);
+	if (ret) {
+		pr_err("%s: failed to register clock notifier for %s\n",
+				__func__, clk_conf->clk_name);
+		return ERR_PTR(-EINVAL);
+	}
+
+	clk = clk_register(NULL, &clk_cpu->hw);
+	if (IS_ERR(clk)) {
+		clk_notifier_unregister(pclk, &clk_cpu->clk_nb);
+		kfree(clk_cpu);
+	}
+
+	return clk;
+}
+