clk: imx: add i.MX93 clk gate

i.MX93 LPCG is different from i.MX8M CCGR. Although imx_clk_hw_gate4_flags
is used here, it not strictly match i.MX93. i.MX93 has such design:
- LPCG_DIRECT use BIT0 as on/off gate when LPCG_AUTHEN CPU_LPM is 0
- LPCG_LPM_CUR use BIT[2:0] as on/off gate when LPCG_AUTHEN CPU_LPM is 1

The current implementation suppose CPU_LPM is 0, and use LPCG_DIRECT
BIT[1:0] as on/off gate. Although BIT1 is touched, actually BIT1 is
reserved.

And imx_clk_hw_gate4_flags use mask 0x3 to determine whether the clk
is enabled or not, but i.MX93 LPCG only use BIT0 to control when CPU_LPM
is 0. So clk disabled unused during kernel boot not able to gate off
the unused clocks.

To match i.MX93 LPCG, introduce imx93_clk_gate.

Signed-off-by: Peng Fan <[e-mail]>
Reviewed-by: Ye Li <[e-mail]>
Reviewed-by: Jacky Bai <[e-mail]>
Reviewed-by: Abel Vesa <[e-mail]>
Signed-off-by: Abel Vesa <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/clk/imx/Makefile

···
 mxc-clk-objs += clk-fixup-mux.o
 mxc-clk-objs += clk-frac-pll.o
 mxc-clk-objs += clk-gate2.o
+mxc-clk-objs += clk-gate-93.o
 mxc-clk-objs += clk-gate-exclusive.o
 mxc-clk-objs += clk-pfd.o
 mxc-clk-objs += clk-pfdv2.o

drivers/clk/imx/clk-gate-93.c

···
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2022 NXP
+ *
+ * Peng Fan <[e-mail]>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/slab.h>
+
+#include "clk.h"
+
+#define DIRECT_OFFSET		0x0
+
+/*
+ * 0b000 - LPCG will be OFF in any CPU mode.
+ * 0b100 - LPCG will be ON in any CPU mode.
+ */
+#define LPM_SETTING_OFF		0x0
+#define LPM_SETTING_ON		0x4
+
+#define LPM_CUR_OFFSET		0x1c
+
+#define AUTHEN_OFFSET		0x30
+#define CPULPM_EN		BIT(2)
+#define TZ_NS_SHIFT		9
+#define TZ_NS_MASK		BIT(9)
+
+#define WHITE_LIST_SHIFT	16
+
+struct imx93_clk_gate {
+	struct clk_hw hw;
+	void __iomem	*reg;
+	u32		bit_idx;
+	u32		val;
+	u32		mask;
+	spinlock_t	*lock;
+	unsigned int	*share_count;
+};
+
+#define to_imx93_clk_gate(_hw) container_of(_hw, struct imx93_clk_gate, hw)
+
+static void imx93_clk_gate_do_hardware(struct clk_hw *hw, bool enable)
+{
+	struct imx93_clk_gate *gate = to_imx93_clk_gate(hw);
+	u32 val;
+
+	val = readl(gate->reg + AUTHEN_OFFSET);
+	if (val & CPULPM_EN) {
+		val = enable ? LPM_SETTING_ON : LPM_SETTING_OFF;
+		writel(val, gate->reg + LPM_CUR_OFFSET);
+	} else {
+		val = readl(gate->reg + DIRECT_OFFSET);
+		val &= ~(gate->mask << gate->bit_idx);
+		if (enable)
+			val |= (gate->val & gate->mask) << gate->bit_idx;
+		writel(val, gate->reg + DIRECT_OFFSET);
+	}
+}
+
+static int imx93_clk_gate_enable(struct clk_hw *hw)
+{
+	struct imx93_clk_gate *gate = to_imx93_clk_gate(hw);
+	unsigned long flags;
+
+	spin_lock_irqsave(gate->lock, flags);
+
+	if (gate->share_count && (*gate->share_count)++ > 0)
+		goto out;
+
+	imx93_clk_gate_do_hardware(hw, true);
+out:
+	spin_unlock_irqrestore(gate->lock, flags);
+
+	return 0;
+}
+
+static void imx93_clk_gate_disable(struct clk_hw *hw)
+{
+	struct imx93_clk_gate *gate = to_imx93_clk_gate(hw);
+	unsigned long flags;
+
+	spin_lock_irqsave(gate->lock, flags);
+
+	if (gate->share_count) {
+		if (WARN_ON(*gate->share_count == 0))
+			goto out;
+		else if (--(*gate->share_count) > 0)
+			goto out;
+	}
+
+	imx93_clk_gate_do_hardware(hw, false);
+out:
+	spin_unlock_irqrestore(gate->lock, flags);
+}
+
+static int imx93_clk_gate_reg_is_enabled(struct imx93_clk_gate *gate)
+{
+	u32 val = readl(gate->reg + AUTHEN_OFFSET);
+
+	if (val & CPULPM_EN) {
+		val = readl(gate->reg + LPM_CUR_OFFSET);
+		if (val == LPM_SETTING_ON)
+			return 1;
+	} else {
+		val = readl(gate->reg);
+		if (((val >> gate->bit_idx) & gate->mask) == gate->val)
+			return 1;
+	}
+
+	return 0;
+}
+
+static int imx93_clk_gate_is_enabled(struct clk_hw *hw)
+{
+	struct imx93_clk_gate *gate = to_imx93_clk_gate(hw);
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(gate->lock, flags);
+
+	ret = imx93_clk_gate_reg_is_enabled(gate);
+
+	spin_unlock_irqrestore(gate->lock, flags);
+
+	return ret;
+}
+
+static void imx93_clk_gate_disable_unused(struct clk_hw *hw)
+{
+	struct imx93_clk_gate *gate = to_imx93_clk_gate(hw);
+	unsigned long flags;
+
+	spin_lock_irqsave(gate->lock, flags);
+
+	if (!gate->share_count || *gate->share_count == 0)
+		imx93_clk_gate_do_hardware(hw, false);
+
+	spin_unlock_irqrestore(gate->lock, flags);
+}
+
+static const struct clk_ops imx93_clk_gate_ops = {
+	.enable = imx93_clk_gate_enable,
+	.disable = imx93_clk_gate_disable,
+	.disable_unused = imx93_clk_gate_disable_unused,
+	.is_enabled = imx93_clk_gate_is_enabled,
+};
+
+static const struct clk_ops imx93_clk_gate_ro_ops = {
+	.is_enabled = imx93_clk_gate_is_enabled,
+};
+
+struct clk_hw *imx93_clk_gate(struct device *dev, const char *name, const char *parent_name,
+			      unsigned long flags, void __iomem *reg, u32 bit_idx, u32 val,
+			      u32 mask, u32 domain_id, unsigned int *share_count)
+{
+	struct imx93_clk_gate *gate;
+	struct clk_hw *hw;
+	struct clk_init_data init;
+	int ret;
+	u32 authen;
+
+	gate = kzalloc(sizeof(struct imx93_clk_gate), GFP_KERNEL);
+	if (!gate)
+		return ERR_PTR(-ENOMEM);
+
+	gate->reg = reg;
+	gate->lock = &imx_ccm_lock;
+	gate->bit_idx = bit_idx;
+	gate->val = val;
+	gate->mask = mask;
+	gate->share_count = share_count;
+
+	init.name = name;
+	init.ops = &imx93_clk_gate_ops;
+	init.flags = flags | CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE;
+	init.parent_names = parent_name ? &parent_name : NULL;
+	init.num_parents = parent_name ? 1 : 0;
+
+	gate->hw.init = &init;
+	hw = &gate->hw;
+
+	authen = readl(reg + AUTHEN_OFFSET);
+	if (!(authen & TZ_NS_MASK) || !(authen & BIT(WHITE_LIST_SHIFT + domain_id)))
+		init.ops = &imx93_clk_gate_ro_ops;
+
+	ret = clk_hw_register(dev, hw);
+	if (ret) {
+		kfree(gate);
+		return ERR_PTR(ret);
+	}
+
+	return hw;
+}
+EXPORT_SYMBOL_GPL(imx93_clk_gate);

drivers/clk/imx/clk.h

···
 	imx93_clk_composite_flags(name, parent_names, num_parents, reg, domain_id \
 				  CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE)
 
+struct clk_hw *imx93_clk_gate(struct device *dev, const char *name, const char *parent_name,
+			      unsigned long flags, void __iomem *reg, u32 bit_idx, u32 val,
+			      u32 mask, u32 domain_id, unsigned int *share_count);
+
 struct clk_hw *imx_clk_hw_divider_gate(const char *name, const char *parent_name,
 		unsigned long flags, void __iomem *reg, u8 shift, u8 width,
 		u8 clk_divider_flags, const struct clk_div_table *table,