[U-Boot] [PATCH V2 05/16] clk: add clk-gate support

[Peng Fan]

Import clk-gate support from Linux Kernel 5.1-rc5

Signed-off-by: Peng Fan <peng.fan at nxp.com>
---

V2:
 Rebase to master

 drivers/clk/Makefile         |   2 +-
 drivers/clk/clk-gate.c       | 148 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/clk-provider.h |  18 ++++++
 3 files changed, 167 insertions(+), 1 deletion(-)
 create mode 100644 drivers/clk/clk-gate.c

diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index b7fec605c6..39154eca59 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -7,7 +7,7 @@
 obj-$(CONFIG_$(SPL_TPL_)CLK) += clk-uclass.o
 obj-$(CONFIG_$(SPL_TPL_)CLK) += clk_fixed_rate.o
 obj-$(CONFIG_$(SPL_TPL_)CLK) += clk_fixed_factor.o
-obj-$(CONFIG_$(SPL_TPL_)CLK_CCF) += clk.o clk-divider.o clk-mux.o
+obj-$(CONFIG_$(SPL_TPL_)CLK_CCF) += clk.o clk-divider.o clk-mux.o clk-gate.o
 obj-$(CONFIG_$(SPL_TPL_)CLK_CCF) += clk-fixed-factor.o
 
 obj-y += analogbits/
diff --git a/drivers/clk/clk-gate.c b/drivers/clk/clk-gate.c
new file mode 100644
index 0000000000..a3a1fdd3b2
--- /dev/null
+++ b/drivers/clk/clk-gate.c
@@ -0,0 +1,148 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr at canonical.com>
+ * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette at linaro.org>
+ * Copyright 2019 NXP
+ *
+ * Gated clock implementation
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <malloc.h>
+#include <clk-uclass.h>
+#include <dm/device.h>
+#include <linux/clk-provider.h>
+#include <clk.h>
+#include "clk.h"
+
+#define UBOOT_DM_CLK_GATE "clk_gate"
+
+/**
+ * DOC: basic gatable clock which can gate and ungate it's output
+ *
+ * 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
+ */
+
+/*
+ * It works on following logic:
+ *
+ * For enabling clock, enable = 1
+ *	set2dis = 1	-> clear bit	-> set = 0
+ *	set2dis = 0	-> set bit	-> set = 1
+ *
+ * For disabling clock, enable = 0
+ *	set2dis = 1	-> set bit	-> set = 1
+ *	set2dis = 0	-> clear bit	-> set = 0
+ *
+ * So, result is always: enable xor set2dis.
+ */
+static void clk_gate_endisable(struct clk *clk, int enable)
+{
+	struct clk_gate *gate = to_clk_gate(clk_dev_binded(clk) ?
+			dev_get_clk_ptr(clk->dev) : clk);
+	int set = gate->flags & CLK_GATE_SET_TO_DISABLE ? 1 : 0;
+	u32 reg;
+
+	set ^= enable;
+
+	if (gate->flags & CLK_GATE_HIWORD_MASK) {
+		reg = BIT(gate->bit_idx + 16);
+		if (set)
+			reg |= BIT(gate->bit_idx);
+	} else {
+		reg = readl(gate->reg);
+
+		if (set)
+			reg |= BIT(gate->bit_idx);
+		else
+			reg &= ~BIT(gate->bit_idx);
+	}
+
+	writel(reg, gate->reg);
+}
+
+static int clk_gate_enable(struct clk *clk)
+{
+	clk_gate_endisable(clk, 1);
+
+	return 0;
+}
+
+static int clk_gate_disable(struct clk *clk)
+{
+	clk_gate_endisable(clk, 0);
+
+	return 0;
+}
+
+int clk_gate_is_enabled(struct clk *clk)
+{
+	struct clk_gate *gate = to_clk_gate(clk_dev_binded(clk) ?
+			dev_get_clk_ptr(clk->dev) : clk);
+	u32 reg;
+
+	reg = readl(gate->reg);
+
+	/* if a set bit disables this clk, flip it before masking */
+	if (gate->flags & CLK_GATE_SET_TO_DISABLE)
+		reg ^= BIT(gate->bit_idx);
+
+	reg &= BIT(gate->bit_idx);
+
+	return reg ? 1 : 0;
+}
+
+const struct clk_ops clk_gate_ops = {
+	.enable = clk_gate_enable,
+	.disable = clk_gate_disable,
+	.get_rate = clk_generic_get_rate,
+};
+
+struct clk *clk_register_gate(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)
+{
+	struct clk_gate *gate;
+	struct clk *clk;
+	int ret;
+
+	if (clk_gate_flags & CLK_GATE_HIWORD_MASK) {
+		if (bit_idx > 15) {
+			pr_err("gate bit exceeds LOWORD field\n");
+			return ERR_PTR(-EINVAL);
+		}
+	}
+
+	/* allocate the gate */
+	gate = kzalloc(sizeof(*gate), GFP_KERNEL);
+	if (!gate)
+		return ERR_PTR(-ENOMEM);
+
+	/* struct clk_gate assignments */
+	gate->reg = reg;
+	gate->bit_idx = bit_idx;
+	gate->flags = clk_gate_flags;
+
+	clk = &gate->clk;
+
+	ret = clk_register(clk, UBOOT_DM_CLK_GATE, name, parent_name);
+	if (ret) {
+		kfree(gate);
+		return ERR_PTR(ret);
+	}
+
+	return clk;
+}
+
+U_BOOT_DRIVER(clk_gate) = {
+	.name	= UBOOT_DM_CLK_GATE,
+	.id	= UCLASS_CLK,
+	.ops	= &clk_gate_ops,
+	.flags = DM_FLAG_PRE_RELOC,
+};
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 6d62f862d2..8b04ecd7a5 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -69,6 +69,24 @@ struct clk_mux {
 extern const struct clk_ops clk_mux_ops;
 u8 clk_mux_get_parent(struct clk *clk);
 
+struct clk_gate {
+	struct clk	clk;
+	void __iomem	*reg;
+	u8		bit_idx;
+	u8		flags;
+};
+
+#define to_clk_gate(_clk) container_of(_clk, struct clk_gate, clk)
+
+#define CLK_GATE_SET_TO_DISABLE		BIT(0)
+#define CLK_GATE_HIWORD_MASK		BIT(1)
+
+extern const struct clk_ops clk_gate_ops;
+struct clk *clk_register_gate(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);
+
 struct clk_div_table {
 	unsigned int	val;
 	unsigned int	div;
-- 
2.16.4