[RFC PATCH 04/50] ARM: at91: add PMC master clock
Boris BREZILLON
b.brezillon at overkiz.com
Fri Jun 7 10:24:12 EDT 2013
This is the at91 master clock implementation using common clk framework.
The pll clock layout describe the MCKR register layout.
There's four pll clock layouts:
- at91rm9200
- at91sam9x5
Master clocks are given characteristics:
- min/max clock output rate
These characteristics are checked during rate change to avoid
over/underclocking.
These characteristics are described in atmel's SoC datasheet in
"Electrical Characteristics" paragraph.
Signed-off-by: Boris BREZILLON <b.brezillon at overkiz.com>
---
drivers/clk/at91/Makefile | 2 +-
drivers/clk/at91/clk-master.c | 317 +++++++++++++++++++++++++++++++++++++++++
include/linux/clk/at91.h | 23 +++
3 files changed, 341 insertions(+), 1 deletion(-)
diff --git a/drivers/clk/at91/Makefile b/drivers/clk/at91/Makefile
index 564076f..d41f616 100644
--- a/drivers/clk/at91/Makefile
+++ b/drivers/clk/at91/Makefile
@@ -2,4 +2,4 @@
# Makefile for at91 specific clk
#
-obj-y += clk-main.o clk-pll.o clk-plldiv.o
+obj-y += clk-main.o clk-pll.o clk-plldiv.o clk-master.o
diff --git a/drivers/clk/at91/clk-master.c b/drivers/clk/at91/clk-master.c
new file mode 100644
index 0000000..71ade7d
--- /dev/null
+++ b/drivers/clk/at91/clk-master.c
@@ -0,0 +1,317 @@
+/*
+ * drivers/clk/at91/clk-master.c
+ *
+ * Copyright (C) 2013 Boris BREZILLON <b.brezillon at overkiz.com>
+ *
+ * This masterram is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/clk/at91.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/io.h>
+
+#define MASTER_SOURCE_MAX 4
+
+#define to_clk_master(hw) container_of(hw, struct clk_master, hw)
+
+struct clk_master {
+ struct clk_hw hw;
+ struct clk_master_layout *layout;
+ struct clk_master_characteristics *characteristics;
+};
+
+static unsigned long clk_master_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ u8 pres;
+ u8 div;
+ unsigned long rate = parent_rate;
+ struct clk_master *master = to_clk_master(hw);
+ struct clk_master_layout *layout = master->layout;
+ struct clk_master_characteristics *characteristics =
+ master->characteristics;
+ u32 tmp = at91_pmc_read(AT91_PMC_MCKR) & layout->mask;
+
+ pres = (tmp >> layout->pres_shift) & 0x7;
+ div = (tmp >> 8) & 0x3;
+
+ if (characteristics->have_div3_pres && pres == 7)
+ rate /= 3;
+ else
+ rate >>= pres;
+
+ rate /= characteristics->divisors[div];
+
+ /* print overclocking or underclocking error */
+ /*
+ if (rate < characteristics->output.min ||
+ rate > characteristics->output.max) {
+ }
+ */
+ return rate;
+}
+
+static long clk_master_round_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *parent_rate)
+{
+ int mdiv;
+ int pres;
+ u32 div;
+ long best_rate = -EINVAL;
+ unsigned long best_diff = 0;
+ unsigned long cur_diff;
+ unsigned long pres_rate;
+ unsigned long cur_rate;
+ struct clk_master *master = to_clk_master(hw);
+ struct clk_master_characteristics *characteristics =
+ master->characteristics;
+
+ if (rate < characteristics->output.min ||
+ rate > characteristics->output.max)
+ return -EINVAL;
+
+ for (pres = 0; pres < 7; pres++) {
+ if (pres < 7)
+ pres_rate = *parent_rate >> pres;
+ else {
+ if (!characteristics->have_div3_pres)
+ break;
+ pres_rate = *parent_rate / 3;
+ }
+ for (mdiv = 0; mdiv < 4; mdiv++) {
+ div = characteristics->divisors[mdiv];
+ if (!div)
+ continue;
+ cur_rate = pres_rate / div;
+ if (rate < cur_rate)
+ cur_diff = cur_rate - rate;
+ else
+ cur_diff = rate - cur_rate;
+
+ if (best_rate < 0 || cur_diff < best_diff) {
+ best_rate = cur_rate;
+ best_diff = cur_diff;
+ if (!best_diff)
+ return best_rate;
+ }
+ }
+ }
+
+ return best_rate;
+}
+
+static int clk_master_set_parent(struct clk_hw *hw, u8 index)
+{
+ u32 tmp;
+ if (index > AT91_PMC_CSS)
+ return -EINVAL;
+ tmp = at91_pmc_read(AT91_PMC_MCKR) & ~AT91_PMC_CSS;
+ tmp |= index;
+
+ at91_pmc_write(AT91_PMC_MCKR, tmp);
+ while (!(at91_pmc_read(AT91_PMC_SR) & AT91_PMC_MCKRDY))
+ ;
+ return 0;
+}
+
+static u8 clk_master_get_parent(struct clk_hw *hw)
+{
+ return at91_pmc_read(AT91_PMC_MCKR) & AT91_PMC_CSS;
+}
+
+static int clk_master_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ int mdiv;
+ int pres;
+ u32 div;
+ u32 tmp;
+ unsigned long cur_rate;
+ unsigned long pres_rate;
+ struct clk_master *master = to_clk_master(hw);
+ struct clk_master_layout *layout = master->layout;
+ struct clk_master_characteristics *characteristics =
+ master->characteristics;
+ for (pres = 0; pres < 7; pres++) {
+ if (pres < 7)
+ pres_rate = parent_rate >> pres;
+ else {
+ if (!characteristics->have_div3_pres)
+ break;
+ pres_rate = parent_rate / 3;
+ }
+ for (mdiv = 0; mdiv < 4; mdiv++) {
+ div = characteristics->divisors[mdiv];
+ if (!div)
+ continue;
+ cur_rate = pres_rate / div;
+ if (cur_rate == rate) {
+ tmp = at91_pmc_read(AT91_PMC_MCKR);
+ tmp &= layout->mask;
+ tmp &= ~AT91_PMC_CSS;
+ tmp |= pres << layout->pres_shift | mdiv << 8;
+
+ at91_pmc_write(AT91_PMC_MCKR, tmp);
+ while (!(at91_pmc_read(AT91_PMC_SR) &
+ AT91_PMC_MCKRDY))
+ ;
+ return 0;
+ }
+ }
+ }
+
+ return -EINVAL;
+}
+
+static const struct clk_ops master_ops = {
+ .recalc_rate = clk_master_recalc_rate,
+ .round_rate = clk_master_round_rate,
+ .get_parent = clk_master_get_parent,
+ .set_parent = clk_master_set_parent,
+ .set_rate = clk_master_set_rate,
+};
+
+struct clk * __init
+at91_clk_register_master(const char *name,
+ int num_parents,
+ const char **parent_names,
+ struct clk_master_layout *layout,
+ struct clk_master_characteristics *characteristics)
+{
+ struct clk_master *master;
+ struct clk *clk = NULL;
+ struct clk_init_data init;
+
+ master = kzalloc(sizeof(*master), GFP_KERNEL);
+ if (!master)
+ return ERR_PTR(-ENOMEM);
+
+ init.name = name;
+ init.ops = &master_ops;
+ init.parent_names = parent_names;
+ init.num_parents = num_parents;
+ init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE;
+
+ master->hw.init = &init;
+ master->layout = layout;
+ master->characteristics = characteristics;
+
+ clk = clk_register(NULL, &master->hw);
+
+ if (IS_ERR(clk))
+ kfree(master);
+
+ return clk;
+}
+
+
+struct clk_master_layout at91rm9200_master_layout = {
+ .mask = 0x31F,
+ .pres_shift = 2,
+};
+
+struct clk_master_layout at91sam9x5_master_layout = {
+ .mask = 0x373,
+ .pres_shift = 4,
+};
+
+
+#if defined(CONFIG_OF)
+static struct clk_master_characteristics * __init
+of_at91_clk_master_get_characteristics(struct device_node *np)
+{
+ int i;
+ u32 tmp;
+ struct clk_master_characteristics *characteristics = NULL;
+
+ characteristics = kzalloc(sizeof(*characteristics), GFP_KERNEL);
+ if (!characteristics)
+ return NULL;
+
+ if (of_property_read_u32_index(np, "output", 0, &tmp))
+ goto out_free_characteristics;
+
+ characteristics->output.min = tmp;
+
+ if (of_property_read_u32_index(np, "output", 1, &tmp))
+ goto out_free_characteristics;
+
+ characteristics->output.max = tmp;
+
+ for (i = 0; i < 4; i++) {
+ tmp = 0;
+ of_property_read_u32_index(np, "divisors", i, &tmp);
+ characteristics->divisors[i] = tmp;
+ }
+
+ characteristics->have_div3_pres =
+ of_property_read_bool(np, "have-div3-pres");
+
+ return characteristics;
+
+out_free_characteristics:
+ kfree(characteristics);
+ return NULL;
+}
+
+static void __init
+of_at91_clk_master_setup(struct device_node *np,
+ struct clk_master_layout *layout)
+{
+ struct clk *clk;
+ int num_parents;
+ int i;
+ const char *parent_names[MASTER_SOURCE_MAX];
+ const char *name = np->name;
+ struct clk_master_characteristics *characteristics;
+
+ num_parents = of_count_phandle_with_args(np, "clocks", "#clock-cells");
+ if (num_parents <= 0 || num_parents > MASTER_SOURCE_MAX)
+ return;
+
+ for (i = 0; i < num_parents; ++i) {
+ parent_names[i] = of_clk_get_parent_name(np, i);
+ if (!parent_names[i])
+ return;
+ }
+
+ of_property_read_string(np, "clock-output-names", &name);
+
+ characteristics = of_at91_clk_master_get_characteristics(np);
+ if (!characteristics)
+ return;
+
+ clk = at91_clk_register_master(name, num_parents, parent_names,
+ layout, characteristics);
+
+ if (IS_ERR(clk))
+ goto out_free_characteristics;
+
+ of_clk_add_provider(np, of_clk_src_simple_get, clk);
+ return;
+
+out_free_characteristics:
+ kfree(characteristics);
+}
+
+static void __init of_at91rm9200_clk_master_setup(struct device_node *np)
+{
+ of_at91_clk_master_setup(np, &at91rm9200_master_layout);
+}
+CLK_OF_DECLARE(at91rm9200_clk_master, "atmel,at91rm9200-clk-master",
+ of_at91rm9200_clk_master_setup);
+
+static void __init of_at91sam9x5_clk_master_setup(struct device_node *np)
+{
+ of_at91_clk_master_setup(np, &at91sam9x5_master_layout);
+}
+CLK_OF_DECLARE(at91sam9x5_clk_master, "atmel,at91sam9x5-clk-master",
+ of_at91sam9x5_clk_master_setup);
+#endif
diff --git a/include/linux/clk/at91.h b/include/linux/clk/at91.h
index 7ba038f..a960e2f 100644
--- a/include/linux/clk/at91.h
+++ b/include/linux/clk/at91.h
@@ -210,6 +210,17 @@ struct clk_pll_layout {
u8 mul_shift;
};
+struct clk_master_characteristics {
+ struct clk_range output;
+ u32 divisors[4];
+ u8 have_div3_pres;
+};
+
+struct clk_master_layout {
+ u32 mask;
+ u8 pres_shift;
+};
+
struct clk * __init
at91_clk_register_main(const char *name,
@@ -233,4 +244,16 @@ at91_clk_register_pll(const char *name, const char *parent_name, u8 id,
struct clk * __init
at91_clk_register_plldiv(const char *name, const char *parent_name);
+
+extern struct clk_master_layout at91rm9200_master_layout;
+
+extern struct clk_master_layout at91sam9x5_master_layout;
+
+struct clk * __init
+at91_clk_register_master(const char *name, int num_parents,
+ const char **parent_names,
+ struct clk_master_layout *layout,
+ struct clk_master_characteristics *characteristics);
+
+
#endif
--
1.7.9.5
More information about the linux-arm-kernel
mailing list