[PATCH v7 09/28] clk: ti: add divider clock driver

[Dario Binacchi <dariobin@libero.it>]

The patch adds support for TI divider clock binding. The driver uses
routines provided by the common clock framework (ccf).

The code is based on the drivers/clk/ti/divider.c driver of the Linux
kernel version 5.9-rc7.
For DT binding details see:
- Documentation/devicetree/bindings/clock/ti/divider.txt

Signed-off-by: Dario Binacchi <dariobin@libero.it>

---

(no changes since v5)

Changes in v5:
- Move the clk-ti.c file to drivers/clk/ti with the name clk.c.
- Move the clk-ti.h file to drivers/clk/ti with the name clk.h.
- Move the clk-ti-divider.c file to drivers/clk/ti with the name
  clk-divider.c.

Changes in v4:
- Include device_compat.h header for dev_xxx macros.
- Fix compilation errors on the dev parameter of the dev_xx macros.

Changes in v3:
- Remove doc/device-tree-bindings/clock/ti,autoidle.txt.
- Remove doc/device-tree-bindings/clock/ti,divider.txt.
- Add to commit message the references to linux kernel dt binding
  documentation.

Changes in v2:
- Merged to patch [09/31] clk: ti: refactor mux and divider clock
  drivers.

 drivers/clk/ti/Kconfig       |   6 +
 drivers/clk/ti/Makefile      |   3 +
 drivers/clk/ti/clk-divider.c | 381 +++++++++++++++++++++++++++++++++++
 drivers/clk/ti/clk-mux.c     |  27 +--
 drivers/clk/ti/clk.c         |  34 ++++
 drivers/clk/ti/clk.h         |  13 ++
 6 files changed, 439 insertions(+), 25 deletions(-)
 create mode 100644 drivers/clk/ti/clk-divider.c
 create mode 100644 drivers/clk/ti/clk.c
 create mode 100644 drivers/clk/ti/clk.h

diff --git a/drivers/clk/ti/Kconfig b/drivers/clk/ti/Kconfig
index c430dd9b8a..87eea86c6f 100644
--- a/drivers/clk/ti/Kconfig
+++ b/drivers/clk/ti/Kconfig
@@ -10,6 +10,12 @@ config CLK_TI_AM3_DPLL
 	  This enables the DPLL clock drivers support on AM33XX SoCs. The DPLL
 	  provides all interface clocks and functional clocks to the processor.
 
+config CLK_TI_DIVIDER
+	bool "TI divider clock driver"
+	depends on CLK && OF_CONTROL && CLK_CCF
+	help
+	  This enables the divider clock driver support on TI's SoCs.
+
 config CLK_TI_MUX
 	bool "TI mux clock driver"
 	depends on CLK && OF_CONTROL && CLK_CCF
diff --git a/drivers/clk/ti/Makefile b/drivers/clk/ti/Makefile
index 9e14b83cfe..fd7094cff0 100644
--- a/drivers/clk/ti/Makefile
+++ b/drivers/clk/ti/Makefile
@@ -3,5 +3,8 @@
 # Copyright (C) 2020 Dario Binacchi <dariobin@libero.it>
 #
 
+obj-$(CONFIG_ARCH_OMAP2PLUS) += clk.o
+
 obj-$(CONFIG_CLK_TI_AM3_DPLL) += clk-am3-dpll.o clk-am3-dpll-x2.o
+obj-$(CONFIG_CLK_TI_DIVIDER) += clk-divider.o
 obj-$(CONFIG_CLK_TI_MUX) += clk-mux.o
diff --git a/drivers/clk/ti/clk-divider.c b/drivers/clk/ti/clk-divider.c
new file mode 100644
index 0000000000..d448197b1f
--- /dev/null
+++ b/drivers/clk/ti/clk-divider.c
@@ -0,0 +1,381 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * TI divider clock support
+ *
+ * Copyright (C) 2020 Dario Binacchi <dariobin@libero.it>
+ *
+ * Loosely based on Linux kernel drivers/clk/ti/divider.c
+ */
+
+#include <common.h>
+#include <clk.h>
+#include <clk-uclass.h>
+#include <div64.h>
+#include <dm.h>
+#include <dm/device_compat.h>
+#include <asm/io.h>
+#include <linux/clk-provider.h>
+#include <linux/kernel.h>
+#include <linux/log2.h>
+#include "clk.h"
+
+/*
+ * The reverse of DIV_ROUND_UP: The maximum number which
+ * divided by m is r
+ */
+#define MULT_ROUND_UP(r, m) ((r) * (m) + (m) - 1)
+
+struct clk_ti_divider_priv {
+	struct clk parent;
+	fdt_addr_t reg;
+	const struct clk_div_table *table;
+	u8 shift;
+	u8 flags;
+	u8 div_flags;
+	s8 latch;
+	u16 min;
+	u16 max;
+	u16 mask;
+};
+
+static unsigned int _get_div(const struct clk_div_table *table, ulong flags,
+			     unsigned int val)
+{
+	if (flags & CLK_DIVIDER_ONE_BASED)
+		return val;
+
+	if (flags & CLK_DIVIDER_POWER_OF_TWO)
+		return 1 << val;
+
+	if (table)
+		return clk_divider_get_table_div(table, val);
+
+	return val + 1;
+}
+
+static unsigned int _get_val(const struct clk_div_table *table, ulong flags,
+			     unsigned int div)
+{
+	if (flags & CLK_DIVIDER_ONE_BASED)
+		return div;
+
+	if (flags & CLK_DIVIDER_POWER_OF_TWO)
+		return __ffs(div);
+
+	if (table)
+		return clk_divider_get_table_val(table, div);
+
+	return div - 1;
+}
+
+static int _div_round_up(const struct clk_div_table *table, ulong parent_rate,
+			 ulong rate)
+{
+	const struct clk_div_table *clkt;
+	int up = INT_MAX;
+	int div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
+
+	for (clkt = table; clkt->div; clkt++) {
+		if (clkt->div == div)
+			return clkt->div;
+		else if (clkt->div < div)
+			continue;
+
+		if ((clkt->div - div) < (up - div))
+			up = clkt->div;
+	}
+
+	return up;
+}
+
+static int _div_round(const struct clk_div_table *table, ulong parent_rate,
+		      ulong rate)
+{
+	if (table)
+		return _div_round_up(table, parent_rate, rate);
+
+	return DIV_ROUND_UP(parent_rate, rate);
+}
+
+static int clk_ti_divider_best_div(struct clk *clk, ulong rate,
+				   ulong *best_parent_rate)
+{
+	struct clk_ti_divider_priv *priv = dev_get_priv(clk->dev);
+	ulong parent_rate, parent_round_rate, max_div;
+	ulong best_rate, r;
+	int i, best_div = 0;
+
+	parent_rate = clk_get_rate(&priv->parent);
+	if (IS_ERR_VALUE(parent_rate))
+		return parent_rate;
+
+	if (!rate)
+		rate = 1;
+
+	if (!(clk->flags & CLK_SET_RATE_PARENT)) {
+		best_div = _div_round(priv->table, parent_rate, rate);
+		if (best_div == 0)
+			best_div = 1;
+
+		if (best_div > priv->max)
+			best_div = priv->max;
+
+		*best_parent_rate = parent_rate;
+		return best_div;
+	}
+
+	max_div = min(ULONG_MAX / rate, (ulong)priv->max);
+	for (best_rate = 0, i = 1; i <= max_div; i++) {
+		if (!clk_divider_is_valid_div(priv->table, priv->div_flags, i))
+			continue;
+
+		/*
+		 * It's the most ideal case if the requested rate can be
+		 * divided from parent clock without needing to change
+		 * parent rate, so return the divider immediately.
+		 */
+		if ((rate * i) == parent_rate) {
+			*best_parent_rate = parent_rate;
+			dev_dbg(clk->dev, "rate=%ld, best_rate=%ld, div=%d\n",
+				rate, rate, i);
+			return i;
+		}
+
+		parent_round_rate = clk_round_rate(&priv->parent,
+						   MULT_ROUND_UP(rate, i));
+		if (IS_ERR_VALUE(parent_round_rate))
+			continue;
+
+		r = DIV_ROUND_UP(parent_round_rate, i);
+		if (r <= rate && r > best_rate) {
+			best_div = i;
+			best_rate = r;
+			*best_parent_rate = parent_round_rate;
+			if (best_rate == rate)
+				break;
+		}
+	}
+
+	if (best_div == 0) {
+		best_div = priv->max;
+		parent_round_rate = clk_round_rate(&priv->parent, 1);
+		if (IS_ERR_VALUE(parent_round_rate))
+			return parent_round_rate;
+	}
+
+	dev_dbg(clk->dev, "rate=%ld, best_rate=%ld, div=%d\n", rate, best_rate,
+		best_div);
+
+	return best_div;
+}
+
+static ulong clk_ti_divider_round_rate(struct clk *clk, ulong rate)
+{
+	ulong parent_rate;
+	int div;
+
+	div = clk_ti_divider_best_div(clk, rate, &parent_rate);
+	if (div < 0)
+		return div;
+
+	return DIV_ROUND_UP(parent_rate, div);
+}
+
+static ulong clk_ti_divider_set_rate(struct clk *clk, ulong rate)
+{
+	struct clk_ti_divider_priv *priv = dev_get_priv(clk->dev);
+	ulong parent_rate;
+	int div;
+	u32 val, v;
+
+	div = clk_ti_divider_best_div(clk, rate, &parent_rate);
+	if (div < 0)
+		return div;
+
+	if (clk->flags & CLK_SET_RATE_PARENT) {
+		parent_rate = clk_set_rate(&priv->parent, parent_rate);
+		if (IS_ERR_VALUE(parent_rate))
+			return parent_rate;
+	}
+
+	val = _get_val(priv->table, priv->div_flags, div);
+
+	v = readl(priv->reg);
+	v &= ~(priv->mask << priv->shift);
+	v |= val << priv->shift;
+	writel(v, priv->reg);
+	clk_ti_latch(priv->reg, priv->latch);
+
+	return clk_get_rate(clk);
+}
+
+static ulong clk_ti_divider_get_rate(struct clk *clk)
+{
+	struct clk_ti_divider_priv *priv = dev_get_priv(clk->dev);
+	ulong rate, parent_rate;
+	unsigned int div;
+	u32 v;
+
+	parent_rate = clk_get_rate(&priv->parent);
+	if (IS_ERR_VALUE(parent_rate))
+		return parent_rate;
+
+	v = readl(priv->reg) >> priv->shift;
+	v &= priv->mask;
+
+	div = _get_div(priv->table, priv->div_flags, v);
+	if (!div) {
+		if (!(priv->div_flags & CLK_DIVIDER_ALLOW_ZERO))
+			dev_warn(clk->dev,
+				 "zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n");
+		return parent_rate;
+	}
+
+	rate = DIV_ROUND_UP(parent_rate, div);
+	dev_dbg(clk->dev, "rate=%ld\n", rate);
+	return rate;
+}
+
+static int clk_ti_divider_request(struct clk *clk)
+{
+	struct clk_ti_divider_priv *priv = dev_get_priv(clk->dev);
+
+	clk->flags = priv->flags;
+	return 0;
+}
+
+const struct clk_ops clk_ti_divider_ops = {
+	.request = clk_ti_divider_request,
+	.round_rate = clk_ti_divider_round_rate,
+	.get_rate = clk_ti_divider_get_rate,
+	.set_rate = clk_ti_divider_set_rate
+};
+
+static int clk_ti_divider_remove(struct udevice *dev)
+{
+	struct clk_ti_divider_priv *priv = dev_get_priv(dev);
+	int err;
+
+	err = clk_release_all(&priv->parent, 1);
+	if (err) {
+		dev_err(dev, "failed to release parent clock\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static int clk_ti_divider_probe(struct udevice *dev)
+{
+	struct clk_ti_divider_priv *priv = dev_get_priv(dev);
+	int err;
+
+	err = clk_get_by_index(dev, 0, &priv->parent);
+	if (err) {
+		dev_err(dev, "failed to get parent clock\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static int clk_ti_divider_ofdata_to_platdata(struct udevice *dev)
+{
+	struct clk_ti_divider_priv *priv = dev_get_priv(dev);
+	struct clk_div_table *table = NULL;
+	u32 val, valid_div;
+	u32 min_div = 0;
+	u32 max_val, max_div = 0;
+	u16 mask;
+	int i, div_num;
+
+	priv->reg = dev_read_addr(dev);
+	dev_dbg(dev, "reg=0x%08lx\n", priv->reg);
+	priv->shift = dev_read_u32_default(dev, "ti,bit-shift", 0);
+	priv->latch = dev_read_s32_default(dev, "ti,latch-bit", -EINVAL);
+	if (dev_read_bool(dev, "ti,index-starts-at-one"))
+		priv->div_flags |= CLK_DIVIDER_ONE_BASED;
+
+	if (dev_read_bool(dev, "ti,index-power-of-two"))
+		priv->div_flags |= CLK_DIVIDER_POWER_OF_TWO;
+
+	if (dev_read_bool(dev, "ti,set-rate-parent"))
+		priv->flags |= CLK_SET_RATE_PARENT;
+
+	if (dev_read_prop(dev, "ti,dividers", &div_num)) {
+		div_num /= sizeof(u32);
+
+		/* Determine required size for divider table */
+		for (i = 0, valid_div = 0; i < div_num; i++) {
+			dev_read_u32_index(dev, "ti,dividers", i, &val);
+			if (val)
+				valid_div++;
+		}
+
+		if (!valid_div) {
+			dev_err(dev, "no valid dividers\n");
+			return -EINVAL;
+		}
+
+		table = calloc(valid_div + 1, sizeof(*table));
+		if (!table)
+			return -ENOMEM;
+
+		for (i = 0, valid_div = 0; i < div_num; i++) {
+			dev_read_u32_index(dev, "ti,dividers", i, &val);
+			if (!val)
+				continue;
+
+			table[valid_div].div = val;
+			table[valid_div].val = i;
+			valid_div++;
+			if (val > max_div)
+				max_div = val;
+
+			if (!min_div || val < min_div)
+				min_div = val;
+		}
+
+		max_val = max_div;
+	} else {
+		/* Divider table not provided, determine min/max divs */
+		min_div = dev_read_u32_default(dev, "ti,min-div", 1);
+		if (dev_read_u32(dev, "ti,max-div", &max_div)) {
+			dev_err(dev, "missing 'max-div' property\n");
+			return -EFAULT;
+		}
+
+		max_val = max_div;
+		if (!(priv->div_flags & CLK_DIVIDER_ONE_BASED) &&
+		    !(priv->div_flags & CLK_DIVIDER_POWER_OF_TWO))
+			max_val--;
+	}
+
+	priv->table = table;
+	priv->min = min_div;
+	priv->max = max_div;
+
+	if (priv->div_flags & CLK_DIVIDER_POWER_OF_TWO)
+		mask = fls(max_val) - 1;
+	else
+		mask = max_val;
+
+	priv->mask = (1 << fls(mask)) - 1;
+	return 0;
+}
+
+static const struct udevice_id clk_ti_divider_of_match[] = {
+	{.compatible = "ti,divider-clock"},
+	{}
+};
+
+U_BOOT_DRIVER(clk_ti_divider) = {
+	.name = "ti_divider_clock",
+	.id = UCLASS_CLK,
+	.of_match = clk_ti_divider_of_match,
+	.ofdata_to_platdata = clk_ti_divider_ofdata_to_platdata,
+	.probe = clk_ti_divider_probe,
+	.remove = clk_ti_divider_remove,
+	.priv_auto_alloc_size = sizeof(struct clk_ti_divider_priv),
+	.ops = &clk_ti_divider_ops,
+};
diff --git a/drivers/clk/ti/clk-mux.c b/drivers/clk/ti/clk-mux.c
index 9720c84513..35470255af 100644
--- a/drivers/clk/ti/clk-mux.c
+++ b/drivers/clk/ti/clk-mux.c
@@ -13,6 +13,7 @@
 #include <clk-uclass.h>
 #include <asm/io.h>
 #include <linux/clk-provider.h>
+#include "clk.h"
 
 struct clk_ti_mux_priv {
 	struct clk_bulk parents;
@@ -24,30 +25,6 @@ struct clk_ti_mux_priv {
 	s32 latch;
 };
 
-static void clk_ti_mux_rmw(u32 val, u32 mask, fdt_addr_t reg)
-{
-	u32 v;
-
-	v = readl(reg);
-	v &= ~mask;
-	v |= val;
-	writel(v, reg);
-}
-
-static void clk_ti_mux_latch(fdt_addr_t reg, s8 shift)
-{
-	u32 latch;
-
-	if (shift < 0)
-		return;
-
-	latch = 1 << shift;
-
-	clk_ti_mux_rmw(latch, latch, reg);
-	clk_ti_mux_rmw(0, latch, reg);
-	readl(reg);		/* OCP barrier */
-}
-
 static struct clk *clk_ti_mux_get_parent_by_index(struct clk_bulk *parents,
 						  int index)
 {
@@ -120,7 +97,7 @@ static int clk_ti_mux_set_parent(struct clk *clk, struct clk *parent)
 
 	val |= index << priv->shift;
 	writel(val, priv->reg);
-	clk_ti_mux_latch(priv->reg, priv->latch);
+	clk_ti_latch(priv->reg, priv->latch);
 	return 0;
 }
 
diff --git a/drivers/clk/ti/clk.c b/drivers/clk/ti/clk.c
new file mode 100644
index 0000000000..e44b90ad6a
--- /dev/null
+++ b/drivers/clk/ti/clk.c
@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * TI clock utilities
+ *
+ * Copyright (C) 2020 Dario Binacchi <dariobin@libero.it>
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include "clk.h"
+
+static void clk_ti_rmw(u32 val, u32 mask, fdt_addr_t reg)
+{
+	u32 v;
+
+	v = readl(reg);
+	v &= ~mask;
+	v |= val;
+	writel(v, reg);
+}
+
+void clk_ti_latch(fdt_addr_t reg, s8 shift)
+{
+	u32 latch;
+
+	if (shift < 0)
+		return;
+
+	latch = 1 << shift;
+
+	clk_ti_rmw(latch, latch, reg);
+	clk_ti_rmw(0, latch, reg);
+	readl(reg);		/* OCP barrier */
+}
diff --git a/drivers/clk/ti/clk.h b/drivers/clk/ti/clk.h
new file mode 100644
index 0000000000..601c3823f7
--- /dev/null
+++ b/drivers/clk/ti/clk.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * TI clock utilities header
+ *
+ * Copyright (C) 2020 Dario Binacchi <dariobin@libero.it>
+ */
+
+#ifndef _CLK_TI_H
+#define _CLK_TI_H
+
+void clk_ti_latch(fdt_addr_t reg, s8 shift);
+
+#endif /* #ifndef _CLK_TI_H */
-- 
2.17.1