clk: ti: add mux clock driver

The driver manages a register-mapped multiplexer with multiple input
clock signals or parents, one of which can be selected as output. It
uses routines provided by the common clock framework (ccf).

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

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

1 files changed, 276 insertions, 0 deletions

diff --git a/drivers/clk/ti/clk-mux.c b/drivers/clk/ti/clk-mux.c
new file mode 100644
index 00000000000..1e22a50910c
--- /dev/null
+++ b/drivers/clk/ti/clk-mux.c
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * TI multiplexer clock support
+ *
+ * Copyright (C) 2020 Dario Binacchi <dariobin@libero.it>
+ *
+ * Based on Linux kernel drivers/clk/ti/mux.c
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <dm/device_compat.h>
+#include <clk-uclass.h>
+#include <asm/io.h>
+#include <linux/clk-provider.h>
+
+struct clk_ti_mux_priv {
+	struct clk_bulk parents;
+	fdt_addr_t reg;
+	u32 flags;
+	u32 mux_flags;
+	u32 mask;
+	u32 shift;
+	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)
+{
+	if (index < 0 || !parents)
+		return ERR_PTR(-EINVAL);
+
+	if (index >= parents->count)
+		return ERR_PTR(-ENODEV);
+
+	return &parents->clks[index];
+}
+
+static int clk_ti_mux_get_parent_index(struct clk_bulk *parents,
+				       struct clk *parent)
+{
+	int i;
+
+	if (!parents || !parent)
+		return -EINVAL;
+
+	for (i = 0; i < parents->count; i++) {
+		if (parents->clks[i].dev == parent->dev)
+			return i;
+	}
+
+	return -ENODEV;
+}
+
+static int clk_ti_mux_get_index(struct clk *clk)
+{
+	struct clk_ti_mux_priv *priv = dev_get_priv(clk->dev);
+	u32 val;
+
+	val = readl(priv->reg);
+	val >>= priv->shift;
+	val &= priv->mask;
+
+	if (val && (priv->flags & CLK_MUX_INDEX_BIT))
+		val = ffs(val) - 1;
+
+	if (val && (priv->flags & CLK_MUX_INDEX_ONE))
+		val--;
+
+	if (val >= priv->parents.count)
+		return -EINVAL;
+
+	return val;
+}
+
+static int clk_ti_mux_set_parent(struct clk *clk, struct clk *parent)
+{
+	struct clk_ti_mux_priv *priv = dev_get_priv(clk->dev);
+	int index;
+	u32 val;
+
+	index = clk_ti_mux_get_parent_index(&priv->parents, parent);
+	if (index < 0) {
+		dev_err(clk->dev, "failed to get parent clock\n");
+		return index;
+	}
+
+	index = clk_mux_index_to_val(NULL, priv->flags, index);
+
+	if (priv->flags & CLK_MUX_HIWORD_MASK) {
+		val = priv->mask << (priv->shift + 16);
+	} else {
+		val = readl(priv->reg);
+		val &= ~(priv->mask << priv->shift);
+	}
+
+	val |= index << priv->shift;
+	writel(val, priv->reg);
+	clk_ti_mux_latch(priv->reg, priv->latch);
+	return 0;
+}
+
+static ulong clk_ti_mux_set_rate(struct clk *clk, ulong rate)
+{
+	struct clk_ti_mux_priv *priv = dev_get_priv(clk->dev);
+	struct clk *parent;
+	int index;
+
+	if ((clk->flags & CLK_SET_RATE_PARENT) == 0)
+		return -ENOSYS;
+
+	index = clk_ti_mux_get_index(clk);
+	parent = clk_ti_mux_get_parent_by_index(&priv->parents, index);
+	if (IS_ERR(parent))
+		return PTR_ERR(parent);
+
+	rate = clk_set_rate(parent, rate);
+	dev_dbg(clk->dev, "rate=%ld\n", rate);
+	return rate;
+}
+
+static ulong clk_ti_mux_get_rate(struct clk *clk)
+{
+	struct clk_ti_mux_priv *priv = dev_get_priv(clk->dev);
+	int index;
+	struct clk *parent;
+	ulong rate;
+
+	index = clk_ti_mux_get_index(clk);
+	parent = clk_ti_mux_get_parent_by_index(&priv->parents, index);
+	if (IS_ERR(parent))
+		return PTR_ERR(parent);
+
+	rate = clk_get_rate(parent);
+	dev_dbg(clk->dev, "rate=%ld\n", rate);
+	return rate;
+}
+
+static ulong clk_ti_mux_round_rate(struct clk *clk, ulong rate)
+{
+	struct clk_ti_mux_priv *priv = dev_get_priv(clk->dev);
+	struct clk *parent;
+	int index;
+
+	if ((clk->flags & CLK_SET_RATE_PARENT) == 0)
+		return -ENOSYS;
+
+	index = clk_ti_mux_get_index(clk);
+	parent = clk_ti_mux_get_parent_by_index(&priv->parents, index);
+	if (IS_ERR(parent))
+		return PTR_ERR(parent);
+
+	rate = clk_round_rate(parent, rate);
+	dev_dbg(clk->dev, "rate=%ld\n", rate);
+	return rate;
+}
+
+static int clk_ti_mux_request(struct clk *clk)
+{
+	struct clk_ti_mux_priv *priv = dev_get_priv(clk->dev);
+	struct clk *parent;
+	int index;
+
+	clk->flags = priv->flags;
+
+	index = clk_ti_mux_get_index(clk);
+	parent = clk_ti_mux_get_parent_by_index(&priv->parents, index);
+	if (IS_ERR(parent))
+		return PTR_ERR(parent);
+
+	return clk_ti_mux_set_parent(clk, parent);
+}
+
+static struct clk_ops clk_ti_mux_ops = {
+	.request = clk_ti_mux_request,
+	.round_rate = clk_ti_mux_round_rate,
+	.get_rate = clk_ti_mux_get_rate,
+	.set_rate = clk_ti_mux_set_rate,
+	.set_parent = clk_ti_mux_set_parent,
+};
+
+static int clk_ti_mux_remove(struct udevice *dev)
+{
+	struct clk_ti_mux_priv *priv = dev_get_priv(dev);
+	int err;
+
+	err = clk_release_all(priv->parents.clks, priv->parents.count);
+	if (err)
+		dev_dbg(dev, "could not release all parents' clocks\n");
+
+	return err;
+}
+
+static int clk_ti_mux_probe(struct udevice *dev)
+{
+	struct clk_ti_mux_priv *priv = dev_get_priv(dev);
+	int err;
+
+	err = clk_get_bulk(dev, &priv->parents);
+	if (err || priv->parents.count < 2) {
+		dev_err(dev, "mux-clock must have parents\n");
+		return err ? err : -EFAULT;
+	}
+
+	/* Generate bit-mask based on parents info */
+	priv->mask = priv->parents.count;
+	if (!(priv->mux_flags & CLK_MUX_INDEX_ONE))
+		priv->mask--;
+
+	priv->mask = (1 << fls(priv->mask)) - 1;
+	return 0;
+}
+
+static int clk_ti_mux_of_to_plat(struct udevice *dev)
+{
+	struct clk_ti_mux_priv *priv = dev_get_priv(dev);
+
+	priv->reg = dev_read_addr(dev);
+	if (priv->reg == FDT_ADDR_T_NONE) {
+		dev_err(dev, "failed to get register\n");
+		return -EINVAL;
+	}
+
+	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);
+
+	priv->flags = CLK_SET_RATE_NO_REPARENT;
+	if (dev_read_bool(dev, "ti,set-rate-parent"))
+		priv->flags |= CLK_SET_RATE_PARENT;
+
+	if (dev_read_bool(dev, "ti,index-starts-at-one"))
+		priv->mux_flags |= CLK_MUX_INDEX_ONE;
+
+	return 0;
+}
+
+static const struct udevice_id clk_ti_mux_of_match[] = {
+	{.compatible = "ti,mux-clock"},
+	{},
+};
+
+U_BOOT_DRIVER(clk_ti_mux) = {
+	.name = "ti_mux_clock",
+	.id = UCLASS_CLK,
+	.of_match = clk_ti_mux_of_match,
+	.ofdata_to_platdata = clk_ti_mux_of_to_plat,
+	.probe = clk_ti_mux_probe,
+	.remove = clk_ti_mux_remove,
+	.priv_auto = sizeof(struct clk_ti_mux_priv),
+	.ops = &clk_ti_mux_ops,
+};