clk: imx: add lpcg clock support

The Low-Power Clock Gate (LPCG) modules contain a local programming
model to control the clock gates for the peripherals. An LPCG module
is used to locally gate the clocks for the associated peripheral.
And they're bedind the SCU clock.

Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Michael Turquette <mturquette@baylibre.com>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/imx/Makefile

@@ -14,7 +14,8 @@ obj-$(CONFIG_MXC_CLK) += \
 	clk-pfd.o
 
 obj-$(CONFIG_MXC_CLK_SCU) += \
-	clk-scu.o
+	clk-scu.o \
+	clk-lpcg-scu.o
 
 obj-$(CONFIG_CLK_IMX8QXP) += clk-imx8qxp.o
 

drivers/clk/imx/clk-lpcg-scu.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2018 NXP
+ *	Dong Aisheng <aisheng.dong@nxp.com>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include "clk-scu.h"
+
+static DEFINE_SPINLOCK(imx_lpcg_scu_lock);
+
+#define CLK_GATE_SCU_LPCG_MASK		0x3
+#define CLK_GATE_SCU_LPCG_HW_SEL	BIT(0)
+#define CLK_GATE_SCU_LPCG_SW_SEL	BIT(1)
+
+/*
+ * struct clk_lpcg_scu - Description of LPCG clock
+ *
+ * @hw: clk_hw of this LPCG
+ * @reg: register of this LPCG clock
+ * @bit_idx: bit index of this LPCG clock
+ * @hw_gate: HW auto gate enable
+ *
+ * This structure describes one LPCG clock
+ */
+struct clk_lpcg_scu {
+	struct clk_hw hw;
+	void __iomem *reg;
+	u8 bit_idx;
+	bool hw_gate;
+};
+
+#define to_clk_lpcg_scu(_hw) container_of(_hw, struct clk_lpcg_scu, hw)
+
+static int clk_lpcg_scu_enable(struct clk_hw *hw)
+{
+	struct clk_lpcg_scu *clk = to_clk_lpcg_scu(hw);
+	unsigned long flags;
+	u32 reg, val;
+
+	spin_lock_irqsave(&imx_lpcg_scu_lock, flags);
+
+	reg = readl_relaxed(clk->reg);
+	reg &= ~(CLK_GATE_SCU_LPCG_MASK << clk->bit_idx);
+
+	val = CLK_GATE_SCU_LPCG_SW_SEL;
+	if (clk->hw_gate)
+		val |= CLK_GATE_SCU_LPCG_HW_SEL;
+
+	reg |= val << clk->bit_idx;
+	writel(reg, clk->reg);
+
+	spin_unlock_irqrestore(&imx_lpcg_scu_lock, flags);
+
+	return 0;
+}
+
+static void clk_lpcg_scu_disable(struct clk_hw *hw)
+{
+	struct clk_lpcg_scu *clk = to_clk_lpcg_scu(hw);
+	unsigned long flags;
+	u32 reg;
+
+	spin_lock_irqsave(&imx_lpcg_scu_lock, flags);
+
+	reg = readl_relaxed(clk->reg);
+	reg &= ~(CLK_GATE_SCU_LPCG_MASK << clk->bit_idx);
+	writel(reg, clk->reg);
+
+	spin_unlock_irqrestore(&imx_lpcg_scu_lock, flags);
+}
+
+static const struct clk_ops clk_lpcg_scu_ops = {
+	.enable = clk_lpcg_scu_enable,
+	.disable = clk_lpcg_scu_disable,
+};
+
+struct clk_hw *imx_clk_lpcg_scu(const char *name, const char *parent_name,
+				unsigned long flags, void __iomem *reg,
+				u8 bit_idx, bool hw_gate)
+{
+	struct clk_lpcg_scu *clk;
+	struct clk_init_data init;
+	struct clk_hw *hw;
+	int ret;
+
+	clk = kzalloc(sizeof(*clk), GFP_KERNEL);
+	if (!clk)
+		return ERR_PTR(-ENOMEM);
+
+	clk->reg = reg;
+	clk->bit_idx = bit_idx;
+	clk->hw_gate = hw_gate;
+
+	init.name = name;
+	init.ops = &clk_lpcg_scu_ops;
+	init.flags = CLK_SET_RATE_PARENT | flags;
+	init.parent_names = parent_name ? &parent_name : NULL;
+	init.num_parents = parent_name ? 1 : 0;
+
+	clk->hw.init = &init;
+
+	hw = &clk->hw;
+	ret = clk_hw_register(NULL, hw);
+	if (ret) {
+		kfree(clk);
+		hw = ERR_PTR(ret);
+	}
+
+	return hw;
+}

drivers/clk/imx/clk-scu.h

@@ -12,4 +12,7 @@
 int imx_clk_scu_init(void);
 struct clk_hw *imx_clk_scu(const char *name, u32 rsrc_id, u8 clk_type);
 
+struct clk_hw *imx_clk_lpcg_scu(const char *name, const char *parent_name,
+				unsigned long flags, void __iomem *reg,
+				u8 bit_idx, bool hw_gate);
 #endif