ARM i.MX: Add common clock support for 2bit gate

This gate consists of two bits:

0b00: clk disabled
0b01: clk enabled in run mode and disabled in sleep mode
0b11: clk enabled

Currently only disabled and enabled are supported. As it's unlikely
that we find something like this in another SoC create a i.MX specific
clk helper for this.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/mach-imx/Makefile

@@ -11,7 +11,7 @@ obj-$(CONFIG_SOC_IMX35) += mm-imx3.o cpu-imx35.o clock-imx35.o ehci-imx35.o pm-i
 
 obj-$(CONFIG_SOC_IMX5) += cpu-imx5.o mm-imx5.o clock-mx51-mx53.o ehci-imx5.o pm-imx5.o cpu_op-mx51.o
 
-obj-$(CONFIG_COMMON_CLK) += clk-pllv1.o clk-pllv2.o clk-pllv3.o
+obj-$(CONFIG_COMMON_CLK) += clk-pllv1.o clk-pllv2.o clk-pllv3.o clk-gate2.o
 
 # Support for CMOS sensor interface
 obj-$(CONFIG_MX1_VIDEO) += mx1-camera-fiq.o mx1-camera-fiq-ksym.o

arch/arm/mach-imx/clk-gate2.c

@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
+ * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
+ *
+ * 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.
+ *
+ * Gated clock implementation
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/string.h>
+
+/**
+ * DOC: basic gatable clock which can gate and ungate it's ouput
+ *
+ * Traits of this clock:
+ * prepare - clk_(un)prepare only ensures parent is (un)prepared
+ * enable - clk_enable and clk_disable are functional & control gating
+ * rate - inherits rate from parent.  No clk_set_rate support
+ * parent - fixed parent.  No clk_set_parent support
+ */
+
+#define to_clk_gate(_hw) container_of(_hw, struct clk_gate, hw)
+
+static int clk_gate2_enable(struct clk_hw *hw)
+{
+	struct clk_gate *gate = to_clk_gate(hw);
+	u32 reg;
+	unsigned long flags = 0;
+
+	if (gate->lock)
+		spin_lock_irqsave(gate->lock, flags);
+
+	reg = readl(gate->reg);
+	reg |= 3 << gate->bit_idx;
+	writel(reg, gate->reg);
+
+	if (gate->lock)
+		spin_unlock_irqrestore(gate->lock, flags);
+
+	return 0;
+}
+
+static void clk_gate2_disable(struct clk_hw *hw)
+{
+	struct clk_gate *gate = to_clk_gate(hw);
+	u32 reg;
+	unsigned long flags = 0;
+
+	if (gate->lock)
+		spin_lock_irqsave(gate->lock, flags);
+
+	reg = readl(gate->reg);
+	reg &= ~(3 << gate->bit_idx);
+	writel(reg, gate->reg);
+
+	if (gate->lock)
+		spin_unlock_irqrestore(gate->lock, flags);
+}
+
+static int clk_gate2_is_enabled(struct clk_hw *hw)
+{
+	u32 reg;
+	struct clk_gate *gate = to_clk_gate(hw);
+
+	reg = readl(gate->reg);
+
+	if (((reg >> gate->bit_idx) & 3) == 3)
+		return 1;
+
+	return 0;
+}
+
+static struct clk_ops clk_gate2_ops = {
+	.enable = clk_gate2_enable,
+	.disable = clk_gate2_disable,
+	.is_enabled = clk_gate2_is_enabled,
+};
+
+struct clk *clk_register_gate2(struct device *dev, const char *name,
+		const char *parent_name, unsigned long flags,
+		void __iomem *reg, u8 bit_idx,
+		u8 clk_gate2_flags, spinlock_t *lock)
+{
+	struct clk_gate *gate;
+	struct clk *clk;
+	struct clk_init_data init;
+
+	gate = kzalloc(sizeof(struct clk_gate), GFP_KERNEL);
+	if (!gate)
+		return ERR_PTR(-ENOMEM);
+
+	/* struct clk_gate assignments */
+	gate->reg = reg;
+	gate->bit_idx = bit_idx;
+	gate->flags = clk_gate2_flags;
+	gate->lock = lock;
+
+	init.name = name;
+	init.ops = &clk_gate2_ops;
+	init.flags = flags;
+	init.parent_names = parent_name ? &parent_name : NULL;
+	init.num_parents = parent_name ? 1 : 0;
+
+	gate->hw.init = &init;
+
+	clk = clk_register(dev, &gate->hw);
+	if (IS_ERR(clk))
+		kfree(clk);
+
+	return clk;
+}

arch/arm/mach-imx/clk.h

@@ -24,6 +24,18 @@ struct clk *imx_clk_pllv3(enum imx_pllv3_type type, const char *name,
 		const char *parent_name, void __iomem *base, u32 gate_mask,
 		u32 div_mask);
 
+struct clk *clk_register_gate2(struct device *dev, const char *name,
+		const char *parent_name, unsigned long flags,
+		void __iomem *reg, u8 bit_idx,
+		u8 clk_gate_flags, spinlock_t *lock);
+
+static inline struct clk *imx_clk_gate2(const char *name, const char *parent,
+		void __iomem *reg, u8 shift)
+{
+	return clk_register_gate2(NULL, name, parent, CLK_SET_RATE_PARENT, reg,
+			shift, 0, &imx_ccm_lock);
+}
+
 static inline struct clk *imx_clk_fixed(const char *name, int rate)
 {
 	return clk_register_fixed_rate(NULL, name, NULL, CLK_IS_ROOT, rate);