[PATCHv7 04/36] CLK: ti: add support for ti divider-clock
Tero Kristo
t-kristo at ti.com
Wed Sep 25 04:48:10 EDT 2013
This patch adds support for TI divider clock binding, which simply uses
the basic clock divider to provide the features needed.
Signed-off-by: Tero Kristo <t-kristo at ti.com>
---
.../devicetree/bindings/clock/ti/divider.txt | 85 ++++++++++
drivers/clk/ti/Makefile | 2 +-
drivers/clk/ti/divider.c | 164 ++++++++++++++++++++
include/linux/clk/ti.h | 2 +
4 files changed, 252 insertions(+), 1 deletion(-)
create mode 100644 Documentation/devicetree/bindings/clock/ti/divider.txt
create mode 100644 drivers/clk/ti/divider.c
diff --git a/Documentation/devicetree/bindings/clock/ti/divider.txt b/Documentation/devicetree/bindings/clock/ti/divider.txt
new file mode 100644
index 0000000..c5eb1f3
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/ti/divider.txt
@@ -0,0 +1,85 @@
+Binding for TI divider clock
+
+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:
+
+ 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.
+
+Required properties:
+- compatible : shall be "divider-clock".
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : link to phandle of parent clock
+- reg : base address for register controlling adjustable divider
+- ti,bit-mask : arbitrary bitmask for programming the 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
+- ti,index-power-of-two : valid divisor programming must be a power of two
+- ti,autoidle-shift : bit shift of the autoidle enable bit for the clock
+- ti,autoidle-low : autoidle is enabled by setting the bit to 0
+- ti,set-rate-parent : clk_set_rate is propagated to parent
+
+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 = <0x4a008190 0x4>;
+ 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 = <0x4a004528 0x4>;
+ ti,max-div = <2>;
+};
diff --git a/drivers/clk/ti/Makefile b/drivers/clk/ti/Makefile
index 533efb4..72a410b 100644
--- a/drivers/clk/ti/Makefile
+++ b/drivers/clk/ti/Makefile
@@ -1,3 +1,3 @@
ifneq ($(CONFIG_OF),)
-obj-y += clk.o dpll.o autoidle.o
+obj-y += clk.o dpll.o autoidle.o divider.o
endif
diff --git a/drivers/clk/ti/divider.c b/drivers/clk/ti/divider.c
new file mode 100644
index 0000000..a97a5d6
--- /dev/null
+++ b/drivers/clk/ti/divider.c
@@ -0,0 +1,164 @@
+/*
+ * TI Divider Clock
+ *
+ * Copyright (C) 2013 Texas Instruments, Inc.
+ *
+ * Tero Kristo <t-kristo at ti.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/clk/ti.h>
+
+struct clk_div_table __init *ti_clk_get_div_table(struct device_node *node)
+{
+ struct clk_div_table *table;
+ const __be32 *divspec;
+ u32 val;
+ u32 num_div;
+ u32 valid_div;
+ int i;
+
+ divspec = of_get_property(node, "ti,dividers", &num_div);
+
+ if (!divspec)
+ return NULL;
+
+ valid_div = 0;
+
+ /* Determine required size for divider table */
+ for (i = 0; i < num_div; i++) {
+ of_property_read_u32_index(node, "ti,dividers", i, &val);
+ if (val)
+ valid_div++;
+ }
+
+ if (!valid_div) {
+ pr_err("%s: no valid dividers for %s table\n", __func__,
+ node->name);
+ return ERR_PTR(-EINVAL);
+ }
+
+ table = kzalloc(sizeof(*table) * (valid_div + 1), GFP_KERNEL);
+
+ if (!table) {
+ pr_err("%s: unable to allocate memory for %s table\n", __func__,
+ node->name);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ valid_div = 0;
+
+ for (i = 0; i < num_div; i++) {
+ of_property_read_u32_index(node, "dividers", i, &val);
+ if (val) {
+ table[valid_div].div = val;
+ table[valid_div].val = i;
+ valid_div++;
+ }
+ }
+
+ return table;
+}
+
+/**
+ * of_ti_divider_clk_setup() - Setup function for simple div rate clock
+ */
+static void __init of_ti_divider_clk_setup(struct device_node *node)
+{
+ struct clk *clk;
+ const char *clk_name = node->name;
+ void __iomem *reg;
+ const char *parent_name;
+ u8 clk_divider_flags = 0;
+ u32 width = 0;
+ u32 shift = 0;
+ struct clk_div_table *table;
+ int min_div, max_div, div;
+ u32 val = 0;
+ u32 flags = 0;
+
+ parent_name = of_clk_get_parent_name(node, 0);
+
+ reg = of_iomap(node, 0);
+ if (!reg) {
+ pr_err("%s: no memory mapped for property reg\n", __func__);
+ return;
+ }
+
+ of_property_read_u32(node, "ti,bit-shift", &shift);
+
+ if (of_property_read_bool(node, "ti,index-starts-at-one"))
+ clk_divider_flags |= CLK_DIVIDER_ONE_BASED;
+
+ if (of_property_read_bool(node, "ti,index-power-of-two"))
+ clk_divider_flags |= CLK_DIVIDER_POWER_OF_TWO;
+
+ if (of_property_read_bool(node, "ti,set-rate-parent"))
+ flags |= CLK_SET_RATE_PARENT;
+
+ table = ti_clk_get_div_table(node);
+
+ if (IS_ERR(table))
+ return;
+
+ if (!table) {
+ /* Clk divider table not provided, determine min/max divs */
+ if (of_property_read_u32(node, "ti,min-div", &min_div)) {
+ pr_debug("%s: ti,min-div not declared for %s, defaulting to 1\n", __func__,
+ node->name);
+ min_div = 1;
+ }
+
+ if (of_property_read_u32(node, "ti,max-div", &max_div)) {
+ pr_err("%s: ti,max-div not declared for %s\n", __func__,
+ node->name);
+ return;
+ }
+
+ /* Determine bit width for the field */
+ if (clk_divider_flags & CLK_DIVIDER_ONE_BASED)
+ val = 1;
+
+ div = min_div;
+
+ while (div < max_div) {
+ if (clk_divider_flags & CLK_DIVIDER_POWER_OF_TWO)
+ div <<= 1;
+ else
+ div++;
+ val++;
+ }
+ } else {
+ div = 0;
+
+ while (table[div].val) {
+ val = table[div].val;
+ div++;
+ }
+ }
+
+ width = fls(val);
+
+ clk = clk_register_divider_table(NULL, clk_name, parent_name, flags,
+ reg, shift, width, clk_divider_flags,
+ table, NULL);
+
+ if (!IS_ERR(clk)) {
+ of_clk_add_provider(node, of_clk_src_simple_get, clk);
+ of_ti_autoidle_setup(node);
+ }
+}
+CLK_OF_DECLARE(divider_clk, "ti,divider-clock", of_ti_divider_clk_setup);
diff --git a/include/linux/clk/ti.h b/include/linux/clk/ti.h
index 6d552c1..7f58f11 100644
--- a/include/linux/clk/ti.h
+++ b/include/linux/clk/ti.h
@@ -182,6 +182,8 @@ int omap3_dpll4_set_rate(struct clk_hw *clk, unsigned long rate,
void ti_dt_clocks_register(struct ti_dt_clk *oclks);
void of_ti_autoidle_setup(struct device_node *node);
+struct clk_div_table *ti_clk_get_div_table(struct device_node *node);
+
#ifdef CONFIG_OF
void of_ti_clk_allow_autoidle_all(void);
void of_ti_clk_deny_autoidle_all(void);
--
1.7.9.5
More information about the linux-arm-kernel
mailing list