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/clk-gate.c b/drivers/clk/clk-gate.c
new file mode 100644
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,
+};