[PATCH] clk: vexpress: Add separate SP810 driver
Pawel Moll
pawel.moll at arm.com
Thu Apr 18 13:23:22 EDT 2013
On Wed, 2013-04-17 at 23:26 +0100, Mike Turquette wrote:
> In this case you are using clk_prepare for one-time configuration. I
> agree that no alternative exists yet, but there have been discussions
> recently about using DT for configuration details that are not strictly
> descriptions of the hardware. I've added a comment block in the patch
> below which notes this with a FIXME since there isn't a graceful
> alternative to using clk_prepare for ont-time configuration.
Fair enough.
> Can you test the patch below against the latest clk-next and let me know
> if it working on your platform?
It wasn't:
WARNING: at [...]/drivers/clk/clk.c:808 __clk_enable+0x94/0xa0()
because the new parent is not prepared automagically. This simple change
heals the problem and now everything is just fine:
/* Switch the parent if necessary */
- if (old_parent != new_parent)
+ if (old_parent != new_parent) {
+ clk_prepare(new_parent);
clk_set_parent(hw->clk, new_parent);
+ clk_unprepare(old_parent);
+ }
So, to summarize, the patch that works for me is below.
Thanks for you help!
Pawel
8<--------------------------------
>From 58807cc1930edd092f1bc54b2ec381ddc9209671 Mon Sep 17 00:00:00 2001
From: Pawel Moll <pawel.moll at arm.com>
Date: Thu, 18 Apr 2013 18:20:54 +0100
Subject: [PATCH] clk: vexpress: Add separate SP810 driver
Factor out the SP810 clocking code into a separate driver,
selecting better (faster) parent at clk_prepare() time.
This is to avoid problems with clocking infrastructure
initialisation order, in particular to avoid dependency
of fixed clock being initialized before SP810. It also
makes vexpress platform OF-based clock initialisation code
unnecessary.
Signed-off-by: Pawel Moll <pawel.moll at arm.com>
Tested-by: Catalin Marinas <catalin.marinas at arm.com>
Signed-off-by: Mike Turquette <mturquette at linaro.org>
[mturquette at linaro.org: add .unprepare, FIXME comment, cleaned up code]
---
arch/arm/mach-vexpress/v2m.c | 8 +-
drivers/clk/versatile/Makefile | 2 +-
drivers/clk/versatile/clk-sp810.c | 188 ++++++++++++++++++++++++++++++++++
drivers/clk/versatile/clk-vexpress.c | 49 ---------
4 files changed, 196 insertions(+), 51 deletions(-)
create mode 100644 drivers/clk/versatile/clk-sp810.c
diff --git a/arch/arm/mach-vexpress/v2m.c b/arch/arm/mach-vexpress/v2m.c
index 915683c..c5e20b5 100644
--- a/arch/arm/mach-vexpress/v2m.c
+++ b/arch/arm/mach-vexpress/v2m.c
@@ -21,6 +21,8 @@
#include <linux/regulator/fixed.h>
#include <linux/regulator/machine.h>
#include <linux/vexpress.h>
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
#include <asm/arch_timer.h>
#include <asm/mach-types.h>
@@ -433,7 +435,7 @@ static void __init v2m_dt_timer_init(void)
{
struct device_node *node = NULL;
- vexpress_clk_of_init();
+ of_clk_init(NULL);
do {
node = of_find_compatible_node(node, NULL, "arm,sp804");
@@ -441,6 +443,10 @@ static void __init v2m_dt_timer_init(void)
if (node) {
pr_info("Using SP804 '%s' as a clock & events source\n",
node->full_name);
+ WARN_ON(clk_register_clkdev(of_clk_get_by_name(node,
+ "timclken1"), "v2m-timer0", "sp804"));
+ WARN_ON(clk_register_clkdev(of_clk_get_by_name(node,
+ "timclken2"), "v2m-timer1", "sp804"));
v2m_sp804_init(of_iomap(node, 0),
irq_of_parse_and_map(node, 0));
}
diff --git a/drivers/clk/versatile/Makefile b/drivers/clk/versatile/Makefile
index ec3b88f..c16ca78 100644
--- a/drivers/clk/versatile/Makefile
+++ b/drivers/clk/versatile/Makefile
@@ -3,5 +3,5 @@ obj-$(CONFIG_ICST) += clk-icst.o
obj-$(CONFIG_ARCH_INTEGRATOR) += clk-integrator.o
obj-$(CONFIG_INTEGRATOR_IMPD1) += clk-impd1.o
obj-$(CONFIG_ARCH_REALVIEW) += clk-realview.o
-obj-$(CONFIG_ARCH_VEXPRESS) += clk-vexpress.o
+obj-$(CONFIG_ARCH_VEXPRESS) += clk-vexpress.o clk-sp810.o
obj-$(CONFIG_VEXPRESS_CONFIG) += clk-vexpress-osc.o
diff --git a/drivers/clk/versatile/clk-sp810.c b/drivers/clk/versatile/clk-sp810.c
new file mode 100644
index 0000000..bf9b15a
--- /dev/null
+++ b/drivers/clk/versatile/clk-sp810.c
@@ -0,0 +1,188 @@
+/*
+ * 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 in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * Copyright (C) 2013 ARM Limited
+ */
+
+#include <linux/amba/sp810.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+#define to_clk_sp810_timerclken(_hw) \
+ container_of(_hw, struct clk_sp810_timerclken, hw)
+
+struct clk_sp810;
+
+struct clk_sp810_timerclken {
+ struct clk_hw hw;
+ struct clk *clk;
+ struct clk_sp810 *sp810;
+ int channel;
+};
+
+struct clk_sp810 {
+ struct device_node *node;
+ int refclk_index, timclk_index;
+ void __iomem *base;
+ spinlock_t lock;
+ struct clk_sp810_timerclken timerclken[4];
+ struct clk *refclk;
+ struct clk *timclk;
+};
+
+static u8 clk_sp810_timerclken_get_parent(struct clk_hw *hw)
+{
+ struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
+ u32 val = readl(timerclken->sp810->base + SCCTRL);
+
+ return !!(val & (1 << SCCTRL_TIMERENnSEL_SHIFT(timerclken->channel)));
+}
+
+static int clk_sp810_timerclken_set_parent(struct clk_hw *hw, u8 index)
+{
+ struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
+ struct clk_sp810 *sp810 = timerclken->sp810;
+ u32 val, shift = SCCTRL_TIMERENnSEL_SHIFT(timerclken->channel);
+ unsigned long flags = 0;
+
+ if (WARN_ON(index > 1))
+ return -EINVAL;
+
+ spin_lock_irqsave(&sp810->lock, flags);
+
+ val = readl(sp810->base + SCCTRL);
+ val &= ~(1 << shift);
+ val |= index << shift;
+ writel(val, sp810->base + SCCTRL);
+
+ spin_unlock_irqrestore(&sp810->lock, flags);
+
+ return 0;
+}
+
+/*
+ * FIXME - setting the parent every time .prepare is invoked is inefficient.
+ * This is better handled by a dedicated clock tree configuration mechanism at
+ * init-time. Revisit this later when such a mechanism exists
+ */
+static int clk_sp810_timerclken_prepare(struct clk_hw *hw)
+{
+ struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
+ struct clk_sp810 *sp810 = timerclken->sp810;
+ struct clk *old_parent = __clk_get_parent(hw->clk);
+ struct clk *new_parent;
+
+ if (!sp810->refclk)
+ sp810->refclk = of_clk_get(sp810->node, sp810->refclk_index);
+
+ if (!sp810->timclk)
+ sp810->timclk = of_clk_get(sp810->node, sp810->timclk_index);
+
+ if (WARN_ON(IS_ERR(sp810->refclk) || IS_ERR(sp810->timclk)))
+ return -ENOENT;
+
+ /* Select fastest parent */
+ if (clk_get_rate(sp810->refclk) > clk_get_rate(sp810->timclk))
+ new_parent = sp810->refclk;
+ else
+ new_parent = sp810->timclk;
+
+ /* Switch the parent if necessary */
+ if (old_parent != new_parent) {
+ clk_prepare(new_parent);
+ clk_set_parent(hw->clk, new_parent);
+ clk_unprepare(old_parent);
+ }
+
+ return 0;
+}
+
+static void clk_sp810_timerclken_unprepare(struct clk_hw *hw)
+{
+ struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
+ struct clk_sp810 *sp810 = timerclken->sp810;
+
+ clk_put(sp810->timclk);
+ clk_put(sp810->refclk);
+}
+
+static const struct clk_ops clk_sp810_timerclken_ops = {
+ .prepare = clk_sp810_timerclken_prepare,
+ .unprepare = clk_sp810_timerclken_unprepare,
+ .get_parent = clk_sp810_timerclken_get_parent,
+ .set_parent = clk_sp810_timerclken_set_parent,
+};
+
+struct clk *clk_sp810_timerclken_of_get(struct of_phandle_args *clkspec,
+ void *data)
+{
+ struct clk_sp810 *sp810 = data;
+
+ if (WARN_ON(clkspec->args_count != 1 || clkspec->args[0] >
+ ARRAY_SIZE(sp810->timerclken)))
+ return NULL;
+
+ return sp810->timerclken[clkspec->args[0]].clk;
+}
+
+void __init clk_sp810_of_setup(struct device_node *node)
+{
+ struct clk_sp810 *sp810 = kzalloc(sizeof(*sp810), GFP_KERNEL);
+ const char *parent_names[2];
+ char name[12];
+ struct clk_init_data init;
+ int i;
+
+ if (!sp810) {
+ pr_err("Failed to allocate memory for SP810!\n");
+ return;
+ }
+
+ sp810->refclk_index = of_property_match_string(node, "clock-names",
+ "refclk");
+ parent_names[0] = of_clk_get_parent_name(node, sp810->refclk_index);
+
+ sp810->timclk_index = of_property_match_string(node, "clock-names",
+ "timclk");
+ parent_names[1] = of_clk_get_parent_name(node, sp810->timclk_index);
+
+ if (parent_names[0] <= 0 || parent_names[1] <= 0) {
+ pr_warn("Failed to obtain parent clocks for SP810!\n");
+ return;
+ }
+
+ sp810->node = node;
+ sp810->base = of_iomap(node, 0);
+ spin_lock_init(&sp810->lock);
+
+ init.name = name;
+ init.ops = &clk_sp810_timerclken_ops;
+ init.flags = CLK_IS_BASIC;
+ init.parent_names = parent_names;
+ init.num_parents = ARRAY_SIZE(parent_names);
+
+ for (i = 0; i < ARRAY_SIZE(sp810->timerclken); i++) {
+ snprintf(name, ARRAY_SIZE(name), "timerclken%d", i);
+
+ sp810->timerclken[i].sp810 = sp810;
+ sp810->timerclken[i].channel = i;
+ sp810->timerclken[i].hw.init = &init;
+
+ sp810->timerclken[i].clk = clk_register(NULL,
+ &sp810->timerclken[i].hw);
+ WARN_ON(IS_ERR(sp810->timerclken[i].clk));
+ }
+
+ of_clk_add_provider(node, clk_sp810_timerclken_of_get, sp810);
+}
+CLK_OF_DECLARE(sp810, "arm,sp810", clk_sp810_of_setup);
diff --git a/drivers/clk/versatile/clk-vexpress.c b/drivers/clk/versatile/clk-vexpress.c
index 82b45aa..a4a728d 100644
--- a/drivers/clk/versatile/clk-vexpress.c
+++ b/drivers/clk/versatile/clk-vexpress.c
@@ -15,8 +15,6 @@
#include <linux/clkdev.h>
#include <linux/clk-provider.h>
#include <linux/err.h>
-#include <linux/of.h>
-#include <linux/of_address.h>
#include <linux/vexpress.h>
static struct clk *vexpress_sp810_timerclken[4];
@@ -86,50 +84,3 @@ void __init vexpress_clk_init(void __iomem *sp810_base)
WARN_ON(clk_register_clkdev(vexpress_sp810_timerclken[1],
"v2m-timer1", "sp804"));
}
-
-#if defined(CONFIG_OF)
-
-struct clk *vexpress_sp810_of_get(struct of_phandle_args *clkspec, void *data)
-{
- if (WARN_ON(clkspec->args_count != 1 || clkspec->args[0] >
- ARRAY_SIZE(vexpress_sp810_timerclken)))
- return NULL;
-
- return vexpress_sp810_timerclken[clkspec->args[0]];
-}
-
-void __init vexpress_clk_of_init(void)
-{
- struct device_node *node;
- struct clk *clk;
- struct clk *refclk, *timclk;
-
- of_clk_init(NULL);
-
- node = of_find_compatible_node(NULL, NULL, "arm,sp810");
- vexpress_sp810_init(of_iomap(node, 0));
- of_clk_add_provider(node, vexpress_sp810_of_get, NULL);
-
- /* Select "better" (faster) parent for SP804 timers */
- refclk = of_clk_get_by_name(node, "refclk");
- timclk = of_clk_get_by_name(node, "timclk");
- if (!WARN_ON(IS_ERR(refclk) || IS_ERR(timclk))) {
- int i = 0;
-
- if (clk_get_rate(refclk) > clk_get_rate(timclk))
- clk = refclk;
- else
- clk = timclk;
-
- for (i = 0; i < ARRAY_SIZE(vexpress_sp810_timerclken); i++)
- WARN_ON(clk_set_parent(vexpress_sp810_timerclken[i],
- clk));
- }
-
- WARN_ON(clk_register_clkdev(vexpress_sp810_timerclken[0],
- "v2m-timer0", "sp804"));
- WARN_ON(clk_register_clkdev(vexpress_sp810_timerclken[1],
- "v2m-timer1", "sp804"));
-}
-
-#endif
--
1.7.10.4
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