[PATCH 08/31] clk: ti: add divider clock driver
Dario Binacchi
dariobin at libero.it
Tue Aug 25 11:21:01 CEST 2020
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.
Signed-off-by: Dario Binacchi <dariobin at libero.it>
---
.../clock/ti,autoidle.txt | 39 ++
doc/device-tree-bindings/clock/ti,divider.txt | 117 +++++
drivers/clk/Kconfig | 6 +
drivers/clk/Makefile | 1 +
drivers/clk/clk-ti-divider.c | 403 ++++++++++++++++++
5 files changed, 566 insertions(+)
create mode 100644 doc/device-tree-bindings/clock/ti,autoidle.txt
create mode 100644 doc/device-tree-bindings/clock/ti,divider.txt
create mode 100644 drivers/clk/clk-ti-divider.c
diff --git a/doc/device-tree-bindings/clock/ti,autoidle.txt b/doc/device-tree-bindings/clock/ti,autoidle.txt
new file mode 100644
index 0000000000..6c5b77e18c
--- /dev/null
+++ b/doc/device-tree-bindings/clock/ti,autoidle.txt
@@ -0,0 +1,39 @@
+Binding for Texas Instruments autoidle clock.
+
+Binding status: Unstable - ABI compatibility may be broken in the future
+
+This binding uses the common clock binding[1]. It assumes a register mapped
+clock which can be put to idle automatically by hardware based on the usage
+and a configuration bit setting. Autoidle clock is never an individual
+clock, it is always a derivative of some basic clock like a gate, divider,
+or fixed-factor.
+
+[1] doc/device-tree-bindings/clock/clock-bindings.txt
+
+Required properties:
+- reg : offset for the register controlling the autoidle
+- ti,autoidle-shift : bit shift of the autoidle enable bit
+- ti,invert-autoidle-bit : autoidle is enabled by setting the bit to 0
+
+Examples:
+ dpll_core_m4_ck: dpll_core_m4_ck {
+ #clock-cells = <0>;
+ compatible = "ti,divider-clock";
+ clocks = <&dpll_core_x2_ck>;
+ ti,max-div = <31>;
+ ti,autoidle-shift = <8>;
+ reg = <0x2d38>;
+ ti,index-starts-at-one;
+ ti,invert-autoidle-bit;
+ };
+
+ dpll_usb_clkdcoldo_ck: dpll_usb_clkdcoldo_ck {
+ #clock-cells = <0>;
+ compatible = "ti,fixed-factor-clock";
+ clocks = <&dpll_usb_ck>;
+ ti,clock-div = <1>;
+ ti,autoidle-shift = <8>;
+ reg = <0x01b4>;
+ ti,clock-mult = <1>;
+ ti,invert-autoidle-bit;
+ };
diff --git a/doc/device-tree-bindings/clock/ti,divider.txt b/doc/device-tree-bindings/clock/ti,divider.txt
new file mode 100644
index 0000000000..3d0570e915
--- /dev/null
+++ b/doc/device-tree-bindings/clock/ti,divider.txt
@@ -0,0 +1,117 @@
+Binding for TI divider clock
+
+Binding status: Unstable - ABI compatibility may be broken in the future
+
+This binding uses the common clock binding[1]. It assumes a
+register-mapped adjustable clock rate divider that does not gate and has
+only one input clock or parent. By default the value programmed into
+the register is one less than the actual divisor value. E.g:
+
+register value actual divisor value
+0 1
+1 2
+2 3
+
+This assumption may be modified by the following optional properties:
+
+ti,index-starts-at-one - valid divisor values start at 1, not the default
+of 0. E.g:
+register value actual divisor value
+1 1
+2 2
+3 3
+
+ti,index-power-of-two - valid divisor values are powers of two. E.g:
+register value actual divisor value
+0 1
+1 2
+2 4
+
+Additionally an array of valid dividers may be supplied like so:
+
+ ti,dividers = <4>, <8>, <0>, <16>;
+
+Which will map the resulting values to a divisor table by their index:
+register value actual divisor value
+0 4
+1 8
+2 <invalid divisor, skipped>
+3 16
+
+Any zero value in this array means the corresponding bit-value is invalid
+and must not be used.
+
+The binding must also provide the register to control the divider and
+unless the divider array is provided, min and max dividers. Optionally
+the number of bits to shift that mask, if necessary. If the shift value
+is missing it is the same as supplying a zero shift.
+
+This binding can also optionally provide support to the hardware autoidle
+feature, see [2].
+
+[1] doc/device-tree-bindings/clock/clock/clock-bindings.txt
+[2] doc/device-tree-bindings/clock/ti,autoidle.txt
+
+Required properties:
+- compatible : shall be "ti,divider-clock" or "ti,composite-divider-clock".
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : link to phandle of parent clock
+- reg : offset for register controlling adjustable divider
+
+Optional properties:
+- clock-output-names : from common clock binding.
+- ti,dividers : array of integers defining divisors
+- ti,bit-shift : number of bits to shift the divider value, defaults to 0
+- ti,min-div : min divisor for dividing the input clock rate, only
+ needed if the first divisor is offset from the default value (1)
+- ti,max-div : max divisor for dividing the input clock rate, only needed
+ if ti,dividers is not defined.
+- ti,index-starts-at-one : valid divisor programming starts at 1, not zero,
+ only valid if ti,dividers is not defined.
+- ti,index-power-of-two : valid divisor programming must be a power of two,
+ only valid if ti,dividers is not defined.
+- ti,autoidle-shift : bit shift of the autoidle enable bit for the clock,
+ see [2]
+- ti,invert-autoidle-bit : autoidle is enabled by setting the bit to 0,
+ see [2]
+- ti,set-rate-parent : clk_set_rate is propagated to parent
+- ti,latch-bit : latch the divider value to HW, only needed if the register
+ access requires this. As an example dra76x DPLL_GMAC H14 divider implements
+ such behavior.
+
+Examples:
+dpll_usb_m2_ck: dpll_usb_m2_ck at 4a008190 {
+ #clock-cells = <0>;
+ compatible = "ti,divider-clock";
+ clocks = <&dpll_usb_ck>;
+ ti,max-div = <127>;
+ reg = <0x190>;
+ ti,index-starts-at-one;
+};
+
+aess_fclk: aess_fclk at 4a004528 {
+ #clock-cells = <0>;
+ compatible = "ti,divider-clock";
+ clocks = <&abe_clk>;
+ ti,bit-shift = <24>;
+ reg = <0x528>;
+ ti,max-div = <2>;
+};
+
+dpll_core_m3x2_div_ck: dpll_core_m3x2_div_ck {
+ #clock-cells = <0>;
+ compatible = "ti,composite-divider-clock";
+ clocks = <&dpll_core_x2_ck>;
+ ti,max-div = <31>;
+ reg = <0x0134>;
+ ti,index-starts-at-one;
+};
+
+ssi_ssr_div_fck_3430es2: ssi_ssr_div_fck_3430es2 {
+ #clock-cells = <0>;
+ compatible = "ti,composite-divider-clock";
+ clocks = <&corex2_fck>;
+ ti,bit-shift = <8>;
+ reg = <0x0a40>;
+ ti,dividers = <0>, <1>, <2>, <3>, <4>, <0>, <6>, <0>, <8>;
+};
diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index bddb454b7c..d7b546d9db 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -105,6 +105,12 @@ 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/Makefile b/drivers/clk/Makefile
index cc20279a20..0fcfcc1837 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -47,6 +47,7 @@ obj-$(CONFIG_SANDBOX) += clk_sandbox_test.o
obj-$(CONFIG_SANDBOX_CLK_CCF) += clk_sandbox_ccf.o
obj-$(CONFIG_STM32H7) += clk_stm32h7.o
obj-$(CONFIG_CLK_TI_AM3_DPLL) += clk-ti-am3-dpll.o clk-ti-am3-dpll-x2.o
+obj-$(CONFIG_CLK_TI_DIVIDER) += clk-ti-divider.o
obj-$(CONFIG_CLK_TI_MUX) += clk-ti-mux.o
obj-$(CONFIG_CLK_TI_SCI) += clk-ti-sci.o
obj-$(CONFIG_CLK_VERSAL) += clk_versal.o
diff --git a/drivers/clk/clk-ti-divider.c b/drivers/clk/clk-ti-divider.c
new file mode 100644
index 0000000000..fa9d60a2d5
--- /dev/null
+++ b/drivers/clk/clk-ti-divider.c
@@ -0,0 +1,403 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * TI divider clock support
+ *
+ * Copyright (C) 2020 Dario Binacchi <dariobin at 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 <asm/io.h>
+#include <linux/clk-provider.h>
+#include <linux/kernel.h>
+#include <linux/log2.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 void clk_ti_divider_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_divider_latch(fdt_addr_t reg, s8 shift)
+{
+ u32 latch;
+
+ if (shift < 0)
+ return;
+
+ latch = 1 << shift;
+
+ clk_ti_divider_rmw(latch, latch, reg);
+ clk_ti_divider_rmw(0, latch, reg);
+ readl(reg); /* OCP barrier */
+}
+
+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 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 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 (!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(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(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_divider_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,
+};
--
2.17.1
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