[PATCH v5 3/4] clk: loongson1: Re-implement the clock driver

[Keguang Zhang]

Re-implement the clock driver for Loongson-1 to
add devicetree support and fit into the clock framework.

Signed-off-by: Keguang Zhang <keguang.zhang@xxxxxxxxx>
---
V4 -> V5: Include the necessary header files
          Add error handling for ls1x_clk_init()
          Remove MODULE_AUTHOR and MODULE_DESCRIPTION
          Some fixes and cleanups
V3 -> V4: Fix the build error of missing linux/module.h
V2 -> V3: Add MODULE_AUTHOR and MODULE_DESCRIPTION info
V1 -> V2: Implement one clock controller instead of single clocks
          (suggested by Krzysztof Kozlowski)
---
 drivers/clk/Makefile        |   1 +
 drivers/clk/clk-loongson1.c | 303 ++++++++++++++++++++++++++++++++++++
 2 files changed, 304 insertions(+)
 create mode 100644 drivers/clk/clk-loongson1.c

diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index b7b2c6d64636..417bc27ab6e8 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -43,6 +43,7 @@ obj-$(CONFIG_COMMON_CLK_K210)		+= clk-k210.o
 obj-$(CONFIG_LMK04832)			+= clk-lmk04832.o
 obj-$(CONFIG_COMMON_CLK_LAN966X)	+= clk-lan966x.o
 obj-$(CONFIG_COMMON_CLK_LOCHNAGAR)	+= clk-lochnagar.o
+obj-$(CONFIG_MACH_LOONGSON32)		+= clk-loongson1.o
 obj-$(CONFIG_COMMON_CLK_MAX77686)	+= clk-max77686.o
 obj-$(CONFIG_COMMON_CLK_MAX9485)	+= clk-max9485.o
 obj-$(CONFIG_ARCH_MILBEAUT_M10V)	+= clk-milbeaut.o
diff --git a/drivers/clk/clk-loongson1.c b/drivers/clk/clk-loongson1.c
new file mode 100644
index 000000000000..c93aa25c8d3a
--- /dev/null
+++ b/drivers/clk/clk-loongson1.c
@@ -0,0 +1,303 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Clock driver for Loongson-1 SoC
+ *
+ * Copyright (C) 2012-2023 Keguang Zhang <keguang.zhang@xxxxxxxxx>
+ */
+
+#include <asm/io.h>
+#include <linux/bits.h>
+#include <linux/clk-provider.h>
+#include <linux/container_of.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/printk.h>
+
+#include <dt-bindings/clock/loongson,ls1x-clk.h>
+
+/* Loongson 1 Clock Register Definitions */
+#define CLK_PLL_FREQ		0x0
+#define CLK_PLL_DIV		0x4
+
+static DEFINE_SPINLOCK(ls1x_clk_div_lock);
+
+struct ls1x_clk_pll_data {
+	u32 fixed;
+	u8 shift;
+	u8 int_shift;
+	u8 int_width;
+	u8 frac_shift;
+	u8 frac_width;
+};
+
+struct ls1x_clk_div_data {
+	u8 shift;
+	u8 width;
+	unsigned long flags;
+	const struct clk_div_table *table;
+	u8 bypass_shift;
+	u8 bypass_inv;
+	spinlock_t *lock;	/* protect access to DIV registers */
+};
+
+struct ls1x_clk {
+	void __iomem *reg;
+	unsigned int offset;
+	struct clk_hw hw;
+	void *data;
+};
+
+#define to_ls1x_clk(_hw) container_of(_hw, struct ls1x_clk, hw)
+
+static inline unsigned long ls1x_pll_rate_part(unsigned int val,
+					       unsigned int shift,
+					       unsigned int width)
+{
+	return (val & GENMASK(shift + width, shift)) >> shift;
+}
+
+static unsigned long ls1x_pll_recalc_rate(struct clk_hw *hw,
+					  unsigned long parent_rate)
+{
+	struct ls1x_clk *ls1x_clk = to_ls1x_clk(hw);
+	const struct ls1x_clk_pll_data *d = ls1x_clk->data;
+	u32 val, rate;
+
+	val = readl(ls1x_clk->reg);
+	rate = d->fixed;
+	rate += ls1x_pll_rate_part(val, d->int_shift, d->int_width);
+	if (d->frac_width)
+		rate += ls1x_pll_rate_part(val, d->frac_shift, d->frac_width);
+	rate *= parent_rate;
+	rate >>= d->shift;
+
+	return rate;
+}
+
+static const struct clk_ops ls1x_pll_clk_ops = {
+	.recalc_rate = ls1x_pll_recalc_rate,
+};
+
+static unsigned long ls1x_divider_recalc_rate(struct clk_hw *hw,
+					      unsigned long parent_rate)
+{
+	struct ls1x_clk *ls1x_clk = to_ls1x_clk(hw);
+	const struct ls1x_clk_div_data *d = ls1x_clk->data;
+	unsigned int val;
+
+	val = readl(ls1x_clk->reg) >> d->shift;
+	val &= clk_div_mask(d->width);
+
+	return divider_recalc_rate(hw, parent_rate, val, d->table,
+				   d->flags, d->width);
+}
+
+static long ls1x_divider_round_rate(struct clk_hw *hw, unsigned long rate,
+				    unsigned long *prate)
+{
+	struct ls1x_clk *ls1x_clk = to_ls1x_clk(hw);
+	const struct ls1x_clk_div_data *d = ls1x_clk->data;
+
+	return divider_round_rate(hw, rate, prate, d->table,
+				  d->width, d->flags);
+}
+
+static int ls1x_divider_set_rate(struct clk_hw *hw, unsigned long rate,
+				 unsigned long parent_rate)
+{
+	struct ls1x_clk *ls1x_clk = to_ls1x_clk(hw);
+	const struct ls1x_clk_div_data *d = ls1x_clk->data;
+	int val, div_val;
+	unsigned long flags = 0;
+
+	div_val = divider_get_val(rate, parent_rate, d->table,
+				  d->width, d->flags);
+	if (div_val < 0)
+		return div_val;
+
+	spin_lock_irqsave(d->lock, flags);
+
+	/* Bypass the clock */
+	val = readl(ls1x_clk->reg);
+	if (d->bypass_inv)
+		val &= ~BIT(d->bypass_shift);
+	else
+		val |= BIT(d->bypass_shift);
+	writel(val, ls1x_clk->reg);
+
+	val = readl(ls1x_clk->reg);
+	val &= ~(clk_div_mask(d->width) << d->shift);
+	val |= (u32)div_val << d->shift;
+	writel(val, ls1x_clk->reg);
+
+	/* Restore the clock */
+	val = readl(ls1x_clk->reg);
+	if (d->bypass_inv)
+		val |= BIT(d->bypass_shift);
+	else
+		val &= ~BIT(d->bypass_shift);
+	writel(val, ls1x_clk->reg);
+
+	spin_unlock_irqrestore(d->lock, flags);
+
+	return 0;
+}
+
+static const struct clk_ops ls1x_clk_divider_ops = {
+	.recalc_rate = ls1x_divider_recalc_rate,
+	.round_rate = ls1x_divider_round_rate,
+	.set_rate = ls1x_divider_set_rate,
+};
+
+#define LS1X_CLK_PLL(_name, _offset, _fixed, _shift,			\
+		     f_shift, f_width, i_shift, i_width)		\
+struct ls1x_clk _name = {						\
+	.offset = (_offset),						\
+	.data = &(struct ls1x_clk_pll_data) {				\
+		.fixed = (_fixed),					\
+		.shift = (_shift),					\
+		.int_shift = (i_shift),					\
+		.int_width = (i_width),					\
+		.frac_shift = (f_shift),				\
+		.frac_width = (f_width),				\
+	},								\
+	.hw.init = &(struct clk_init_data) {				\
+		.name = #_name,						\
+		.ops = &ls1x_pll_clk_ops,				\
+		.parent_data = &(const struct clk_parent_data) {	\
+			.fw_name = "xtal",				\
+			.name = "xtal",					\
+			.index = -1,					\
+		},							\
+		.num_parents = 1,					\
+	},								\
+}
+
+#define LS1X_CLK_DIV(_name, _pname, _offset, _shift, _width,		\
+		     _table, _bypass_shift, _bypass_inv, _flags)	\
+struct ls1x_clk _name = {						\
+	.offset = (_offset),						\
+	.data = &(struct ls1x_clk_div_data){				\
+		.shift = (_shift),					\
+		.width = (_width),					\
+		.table = (_table),					\
+		.flags = (_flags),					\
+		.bypass_shift = (_bypass_shift),			\
+		.bypass_inv = (_bypass_inv),				\
+		.lock = &ls1x_clk_div_lock,				\
+	},								\
+	.hw.init = &(const struct clk_init_data) {				\
+		.name = #_name,						\
+		.ops = &ls1x_clk_divider_ops,				\
+		.parent_hws = (const struct clk_hw *[]) { _pname },	\
+		.num_parents = 1,					\
+		.flags = CLK_GET_RATE_NOCACHE,				\
+	},								\
+}
+
+static LS1X_CLK_PLL(ls1b_clk_pll, CLK_PLL_FREQ, 12, 1, 0, 5, 0, 0);
+static LS1X_CLK_DIV(ls1b_clk_cpu, &ls1b_clk_pll.hw, CLK_PLL_DIV,
+		    20, 4, NULL, 8, 0,
+		    CLK_DIVIDER_ONE_BASED | CLK_DIVIDER_ROUND_CLOSEST);
+static LS1X_CLK_DIV(ls1b_clk_dc, &ls1b_clk_pll.hw, CLK_PLL_DIV,
+		    26, 4, NULL, 12, 0, CLK_DIVIDER_ONE_BASED);
+static LS1X_CLK_DIV(ls1b_clk_ahb, &ls1b_clk_pll.hw, CLK_PLL_DIV,
+		    14, 4, NULL, 10, 0, CLK_DIVIDER_ONE_BASED);
+static CLK_FIXED_FACTOR(ls1b_clk_apb, "ls1b_clk_apb", "ls1b_clk_ahb", 2, 1,
+			CLK_SET_RATE_PARENT);
+
+static struct clk_hw_onecell_data ls1b_clk_hw_data = {
+	.hws = {
+		[LS1X_CLKID_PLL] = &ls1b_clk_pll.hw,
+		[LS1X_CLKID_CPU] = &ls1b_clk_cpu.hw,
+		[LS1X_CLKID_DC] = &ls1b_clk_dc.hw,
+		[LS1X_CLKID_AHB] = &ls1b_clk_ahb.hw,
+		[LS1X_CLKID_APB] = &ls1b_clk_apb.hw,
+	},
+	.num = CLK_NR_CLKS,
+};
+
+static const struct clk_div_table ls1c_ahb_div_table[] = {
+	[0] = { .val = 0, .div = 2 },
+	[1] = { .val = 1, .div = 4 },
+	[2] = { .val = 2, .div = 3 },
+	[3] = { .val = 3, .div = 3 },
+	[4] = { /* sentinel */ }
+};
+
+static LS1X_CLK_PLL(ls1c_clk_pll, CLK_PLL_FREQ, 0, 2, 8, 8, 16, 8);
+static LS1X_CLK_DIV(ls1c_clk_cpu, &ls1c_clk_pll.hw, CLK_PLL_DIV,
+		    8, 7, NULL, 0, 1,
+		    CLK_DIVIDER_ONE_BASED | CLK_DIVIDER_ROUND_CLOSEST);
+static LS1X_CLK_DIV(ls1c_clk_dc, &ls1c_clk_pll.hw, CLK_PLL_DIV,
+		    24, 7, NULL, 4, 1, CLK_DIVIDER_ONE_BASED);
+static LS1X_CLK_DIV(ls1c_clk_ahb, &ls1c_clk_cpu.hw, CLK_PLL_FREQ,
+		    0, 2, ls1c_ahb_div_table, 0, 0, CLK_DIVIDER_ALLOW_ZERO);
+static CLK_FIXED_FACTOR(ls1c_clk_apb, "ls1c_clk_apb", "ls1c_clk_ahb", 1, 1,
+			CLK_SET_RATE_PARENT);
+
+static struct clk_hw_onecell_data ls1c_clk_hw_data = {
+	.hws = {
+		[LS1X_CLKID_PLL] = &ls1c_clk_pll.hw,
+		[LS1X_CLKID_CPU] = &ls1c_clk_cpu.hw,
+		[LS1X_CLKID_DC] = &ls1c_clk_dc.hw,
+		[LS1X_CLKID_AHB] = &ls1c_clk_ahb.hw,
+		[LS1X_CLKID_APB] = &ls1c_clk_apb.hw,
+	},
+	.num = CLK_NR_CLKS,
+};
+
+static void __init ls1x_clk_init(struct device_node *np,
+				 struct clk_hw_onecell_data *hw_data)
+{
+	struct ls1x_clk *ls1x_clk;
+	void __iomem *reg;
+	int i, ret;
+
+	reg = of_iomap(np, 0);
+	if (!reg) {
+		pr_err("Unable to map base for %pOF\n", np);
+		return;
+	}
+
+	for (i = 0; i < hw_data->num; i++) {
+		/* array might be sparse */
+		if (!hw_data->hws[i])
+			continue;
+
+		if (i != LS1X_CLKID_APB) {
+			ls1x_clk = to_ls1x_clk(hw_data->hws[i]);
+			ls1x_clk->reg = reg + ls1x_clk->offset;
+		}
+
+		ret = of_clk_hw_register(np, hw_data->hws[i]);
+		if (ret)
+			goto err;
+	}
+
+	ret = of_clk_add_hw_provider(np, of_clk_hw_onecell_get, hw_data);
+	if (!ret)
+		return;
+
+err:
+	pr_err("Failed to register %pOF\n", np);
+
+	while (--i >= 0)
+		clk_hw_unregister(hw_data->hws[i]);
+
+	iounmap(reg);
+}
+
+static void __init ls1b_clk_init(struct device_node *np)
+{
+	return ls1x_clk_init(np, &ls1b_clk_hw_data);
+}
+
+static void __init ls1c_clk_init(struct device_node *np)
+{
+	return ls1x_clk_init(np, &ls1c_clk_hw_data);
+}
+
+CLK_OF_DECLARE(ls1b_clk, "loongson,ls1b-clk", ls1b_clk_init);
+CLK_OF_DECLARE(ls1c_clk, "loongson,ls1c-clk", ls1c_clk_init);
-- 
2.34.1