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SubjectRe: [PATCH v10 05/17] clk: tegra: Introduce ability for SoC-specific reset control callbacks
On 05/19/2015 05:59 PM, Thierry Reding wrote:
> On Tue, May 19, 2015 at 02:39:27PM +0300, Mikko Perttunen wrote:
>> This patch allows SoC-specific CAR initialization routines to register
>> their own reset_assert and reset_deassert callbacks with the common Tegra
>> CAR code. If defined, the common code will call these callbacks when a
>> reset control with number >= num_periph_banks * 32 is attempted to be asserted
>> or deasserted respectively. Numbers greater than or equal to num_periph_banks * 32
>> are used to avoid clashes with low numbers that are automatically mapped to
>> standard CAR reset lines.
>>
>> Each SoC with these special resets should specify the defined reset control
>> numbers in a device tree header file.
>
> This is looking pretty good, but I think we can simplify a wee bit
> more...
>
>> Signed-off-by: Mikko Perttunen <mikko.perttunen@kapsi.fi>
>> Acked-by: Michael Turquette <mturquette@linaro.org>
>> ---
>> drivers/clk/tegra/clk.c | 39 +++++++++++++++++++++++++++++++--------
>> drivers/clk/tegra/clk.h | 3 +++
>> 2 files changed, 34 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/clk/tegra/clk.c b/drivers/clk/tegra/clk.c
>> index 41cd87c..c093ed9 100644
>> --- a/drivers/clk/tegra/clk.c
>> +++ b/drivers/clk/tegra/clk.c
>> @@ -49,7 +49,6 @@
>> #define RST_DEVICES_L 0x004
>> #define RST_DEVICES_H 0x008
>> #define RST_DEVICES_U 0x00C
>> -#define RST_DFLL_DVCO 0x2F4
>> #define RST_DEVICES_V 0x358
>> #define RST_DEVICES_W 0x35C
>> #define RST_DEVICES_X 0x28C
>> @@ -79,6 +78,11 @@ static struct clk **clks;
>> static int clk_num;
>> static struct clk_onecell_data clk_data;
>>
>> +/* Handlers for SoC-specific reset lines */
>> +static int (*special_reset_assert)(unsigned long);
>> +static int (*special_reset_deassert)(unsigned long);
>> +static int special_reset_num;
>
> I think we can get rid of this if we...
>
>> +
>> static struct tegra_clk_periph_regs periph_regs[] = {
>> [0] = {
>> .enb_reg = CLK_OUT_ENB_L,
>> @@ -152,19 +156,29 @@ static int tegra_clk_rst_assert(struct reset_controller_dev *rcdev,
>> */
>> tegra_read_chipid();
>>
>> - writel_relaxed(BIT(id % 32),
>> - clk_base + periph_regs[id / 32].rst_set_reg);
>> + if (id < periph_banks * 32) {
>> + writel_relaxed(BIT(id % 32),
>> + clk_base + periph_regs[id / 32].rst_set_reg);
>> + return 0;
>> + } else if (id < periph_banks * 32 + special_reset_num) {
>> + return special_reset_assert(id);
>> + }
>
> ... pass id - periph_banks * 32 into special_reset_assert(). Oh, but
> then...

The reason I don't subtract periph_banks * 32 is because this way the
code in the SoC-specific callback can just include the dt-bindings
header and use the same defines used in the device tree.

>
>> @@ -286,10 +300,19 @@ void __init tegra_add_of_provider(struct device_node *np)
>> of_clk_add_provider(np, of_clk_src_onecell_get, &clk_data);
>>
>> rst_ctlr.of_node = np;
>> - rst_ctlr.nr_resets = periph_banks * 32;
>> + rst_ctlr.nr_resets = periph_banks * 32 + special_reset_num;
>
> ... this is no longer going to work. We could keep special_reset_num,
> though obviously it should be an unsigned int and renamed to
> num_special_reset, yet still pass the relative ID into the SoC-specific
> callbacks, after all that's what they care about and each implementation
> would have to subtract periph_banks * 32 anyway.

Mostly agreed, but see above :)

>
>> reset_controller_register(&rst_ctlr);
>> }
>>
>> +void __init tegra_init_special_resets(int num,
>> + int (*assert)(unsigned long),
>> + int (*deassert)(unsigned long))
>> +{
>> + special_reset_num = num;
>> + special_reset_assert = assert;
>> + special_reset_deassert = deassert;
>> +}
>> +
>
> I think we could possibly improve this interface somewhat by turning it
> upside-down, that is, make SoC-specific drivers call this in a helper
> fashion. But this is good enough for now, I can always take a stab at
> refactoring if I get bored.
>
> Thierry
>

Thanks,
Mikko



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