clk: add clk-gate support

Import clk-gate support from Linux Kernel 5.1-rc5

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

diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index b7fec605c6ced602dcc19dab63be35f26977134c..39154eca59c3212389fbeea3205ae85f4c8094cb 100644 (file)
--- 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 (file)
index 0000000..a3a1fdd
--- /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@canonical.com>
+ * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@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 6d62f862d2aaa7c2a014d383d7d5c16e77dffc7b..8b04ecd7a5c7190f35f8f44318ae5d00a46bf288 100644 (file)
--- 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;