[PATCH] clk: vexpress: Add separate SP810 driver
Mike Turquette
mturquette at linaro.org
Thu Apr 18 16:22:10 EDT 2013
Quoting Pawel Moll (2013-04-18 10:23:22)
> 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.
>
Ah yes, that's a bit tricky. All of the parents of the sp810 clk will
have prepare_count >= 1, but not the sp810 clk itself when this code is
executed. Otherwise clk_set_prepare would have migrated the
prepare_count(s) over automagically. Another reason to revisit this
code some day.
I've gone ahead and merged the patch below.
Thanks!
Mike
> 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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