linux-kernel - Re: [PATCH 07/26] clk: vt8500: parse pmc

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Message-ID: <523B4A51.4020704@prisktech.co.nz>
Date:	Fri, 20 Sep 2013 07:02:41 +1200
From:	Tony Prisk <linux@...sktech.co.nz>
To:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
CC:	Olof Johansson <olof@...om.net>, Arnd Bergmann <arnd@...db.de>,
	Mike Turquette <mturquette@...aro.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 07/26] clk: vt8500: parse pmc_base from clock driver

On 19/09/13 05:53, Sebastian Hesselbarth wrote:
> Currently, clock providers for vt8500 depend on machine_init providing
> pmc_base address before calling of_clk_init. With upcoming arch-wide
> .time_init calling of_clk_init, we should make clock providers independent
> of mach code. This adds a pmc_base parsing helper to current clock provider
> that gets called if there is no pmc_base set, yet.
>
> Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
> ---
> Cc: Olof Johansson <olof@...om.net>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Tony Prisk <linux@...sktech.co.nz>
> Cc: Mike Turquette <mturquette@...aro.org>
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> ---
>   drivers/clk/clk-vt8500.c |   21 +++++++++++++++++++++
>   1 file changed, 21 insertions(+)
>
> diff --git a/drivers/clk/clk-vt8500.c b/drivers/clk/clk-vt8500.c
> index 82306f5..a5ee01c 100644
> --- a/drivers/clk/clk-vt8500.c
> +++ b/drivers/clk/clk-vt8500.c
> @@ -15,11 +15,14 @@
>   
>   #include <linux/io.h>
>   #include <linux/of.h>
> +#include <linux/of_address.h>
>   #include <linux/slab.h>
>   #include <linux/bitops.h>
>   #include <linux/clkdev.h>
>   #include <linux/clk-provider.h>
>   
> +#define LEGACY_PMC_BASE		0xD8130000
> +
>   /* All clocks share the same lock as none can be changed concurrently */
>   static DEFINE_SPINLOCK(_lock);
>   
> @@ -626,6 +629,21 @@ const struct clk_ops vtwm_pll_ops = {
>   	.recalc_rate = vtwm_pll_recalc_rate,
>   };
>   
> +static __init void vtwm_set_pmc_base(void)
> +{
> +	struct device_node *np =
> +		of_find_compatible_node(NULL, NULL, "via,vt8500-pmc");
> +
> +	if (np)
> +		pmc_base = of_iomap(np, 0);
> +	else
> +		pmc_base = ioremap(LEGACY_PMC_BASE, 0x1000);
> +	of_node_put(np);
> +
> +	if (!pmc_base)
> +		pr_err("%s:of_iomap(pmc) failed\n", __func__);
> +}
> +
>   static __init void vtwm_pll_clk_init(struct device_node *node, int pll_type)
>   {
>   	u32 reg;
> @@ -636,6 +654,9 @@ static __init void vtwm_pll_clk_init(struct device_node *node, int pll_type)
>   	struct clk_init_data init;
>   	int rc;
>   
> +	if (!pmc_base)
> +		vtwm_set_pmc_base();
> +
>   	rc = of_property_read_u32(node, "reg", &reg);
>   	if (WARN_ON(rc))
>   		return;
What happens if the first clock registered is a 'device clock' rather 
than a 'pll'?

static __init void vtwm_device_clk_init(struct device_node *node)
{
     u32 en_reg, div_reg;
     struct clk *clk;
     struct clk_device *dev_clk;
     const char *clk_name = node->name;
     const char *parent_name;
     struct clk_init_data init;
     int rc;
     int clk_init_flags = 0;

     dev_clk = kzalloc(sizeof(*dev_clk), GFP_KERNEL);
     if (WARN_ON(!dev_clk))
         return;

     dev_clk->lock = &_lock;

     rc = of_property_read_u32(node, "enable-reg", &en_reg);
     if (!rc) {
         dev_clk->en_reg = pmc_base + en_reg;
...
}
CLK_OF_DECLARE(vt8500_device, "via,vt8500-device-clock", 
vtwm_device_clk_init);

If a device clock is initialized first, pmc_base will be null and 
dev_clk->en_reg (+ other register offsets) will be incorrect.


Regards
Tony Prisk
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