[PATCH linux dev-4.17 v2] clk: aspeed: Support HPLL strapping on ast2400

[Joel Stanley]

On 25 June 2018 at 10:41, Andrew Jeffery <andrew at aj.id.au> wrote:
> On Thu, 21 Jun 2018, at 16:55, Joel Stanley wrote:
>> The HPLL can be configured through a register (SCU24), however some
>> platforms chose to configure it through the strapping settings and do
>> not use the register. This was not noticed as the logic for bit 18 in
>> SCU24 was confused: set means programmed, but the driver read it as set
>> means strapped.
>>
>> This gives us the correct HPLL value on Palmetto systems, from which
>> most of the peripheral clocks are generated.
>>
>> Signed-off-by: Joel Stanley <joel at jms.id.au>
>> ---
>> v2: Fix comment and commit message
>> ---
>>  drivers/clk/clk-aspeed.c | 22 +++++++++++++++++++---
>>  1 file changed, 19 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/clk/clk-aspeed.c b/drivers/clk/clk-aspeed.c
>> index c17032bc853a..7d8cc412959d 100644
>> --- a/drivers/clk/clk-aspeed.c
>> +++ b/drivers/clk/clk-aspeed.c
>> @@ -24,7 +24,7 @@
>>  #define ASPEED_MPLL_PARAM    0x20
>>  #define ASPEED_HPLL_PARAM    0x24
>>  #define  AST2500_HPLL_BYPASS_EN      BIT(20)
>> -#define  AST2400_HPLL_STRAPPED       BIT(18)
>> +#define  AST2400_HPLL_PROGRAMMED BIT(18)
>>  #define  AST2400_HPLL_BYPASS_EN      BIT(17)
>>  #define ASPEED_MISC_CTRL     0x2c
>>  #define  UART_DIV13_EN               BIT(12)
>> @@ -586,8 +586,24 @@ static void __init aspeed_ast2400_cc(struct regmap *map)
>>        * and we assume that it is enabled
>>        */
>>       regmap_read(map, ASPEED_HPLL_PARAM, &val);
>> -     WARN(val & AST2400_HPLL_STRAPPED, "hpll is strapped not configured");
>> -     aspeed_clk_data->hws[ASPEED_CLK_HPLL] = aspeed_ast2400_calc_pll("hpll", val);
>> +     if (val & AST2400_HPLL_PROGRAMMED) {
>> +             aspeed_clk_data->hws[ASPEED_CLK_HPLL] =
>> +                     aspeed_ast2400_calc_pll("hpll", val);
>> +     } else {
>> +             /* hpll is configured by the strap register */
>> +             regmap_read(map, ASPEED_STRAP, &val);
>> +             val = (val >> 8) & 0x3;
>> +             if (val == 0x00)
>> +                     freq = 384000000;
>> +             else if (val == 0x01)
>> +                     freq = 360000000;
>> +             else if (val == 0x02)
>> +                     freq = 336000000;
>> +             else if (val == 0x03)
>> +                     freq = 408000000;
>> +             aspeed_clk_data->hws[ASPEED_CLK_HPLL] =
>> +                     clk_hw_register_fixed_rate(NULL, "hpll", "clkin", 0, freq);
>> +     }
>
> Logic looks fine, but I feel this might be better as a lookup table. Bikeshed will be hot pink.

I anticipated your review, and sent v3 last week with a lookup table.
I also merged it into the openbmc tree :)