RE: [PATCH 01/10] clk: aspeed: ast2600: Porting sdhci clock source

[Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>]

Hi Paul,

> -----Original Message-----
> From: Paul Menzel <pmenzel@molgen.mpg.de>
> Sent: Tuesday, October 26, 2021 2:10 PM
> To: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
> Cc: robh+dt@kernel.org; joel@jms.id.au; mturquette@baylibre.com;
> sboyd@kernel.org; adrian.hunter@intel.com; linux-aspeed@lists.ozlabs.org;
> openbmc@lists.ozlabs.org; linux-mmc@vger.kernel.org;
> devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> linux-kernel@vger.kernel.org; linux-clk@vger.kernel.org; andrew@aj.id.au;
> BMC-SW <BMC-SW@aspeedtech.com>; Steven Lee
> <steven_lee@aspeedtech.com>
> Subject: Re: [PATCH 01/10] clk: aspeed: ast2600: Porting sdhci clock source
> 
> Dear Chin-Ting,
> 
> 
> Thank you for your patch. Some small things.
> 
> Please use imperative mood in the commit messages summary [1]:
> 
> clk: aspeed: ast2600: Port SDHCI clock source

Okay.

> On 22.09.21 12:31, Chin-Ting Kuo wrote:
> > - There are two clock sources used to generate
> >    SD/SDIO clock, APLL clock and HCLK (200MHz).
> >    User can select which clock source should be used
> >    by configuring SCU310[8].
> > - The SD/SDIO clock divider selection table SCU310[30:28]
> >    is different between AST2600-A1 and AST2600-A2/A3.
> >    For AST2600-A1, 200MHz SD/SDIO clock cannot be
> >    gotten by the dividers in SCU310[30:28] if APLL
> >    is not the multiple of 200MHz and HCLK is 200MHz.
> >    For AST2600-A2/A3, a new divider, "1", is added and
> >    200MHz SD/SDIO clock can be obtained by adopting HCLK
> >    as clock source and setting SCU310[30:28] to 3b'111.
> 
> Please reference the datasheet name and version, and please reflow the
> commit message for 75 characters per line.
> 

Okay, it will be updated in the next patch version.

> > Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
> > ---
> >   drivers/clk/clk-ast2600.c | 69
> ++++++++++++++++++++++++++++++++++-----
> >   1 file changed, 61 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/clk/clk-ast2600.c b/drivers/clk/clk-ast2600.c
> > index bc3be5f3eae1..a6778c18274a 100644
> > --- a/drivers/clk/clk-ast2600.c
> > +++ b/drivers/clk/clk-ast2600.c
> > @@ -168,6 +168,30 @@ static const struct clk_div_table ast2600_div_table[]
> = {
> >   	{ 0 }
> >   };
> >
> > +static const struct clk_div_table ast2600_sd_div_a1_table[] = {
> > +	{ 0x0, 2 },
> > +	{ 0x1, 4 },
> > +	{ 0x2, 6 },
> > +	{ 0x3, 8 },
> > +	{ 0x4, 10 },
> > +	{ 0x5, 12 },
> > +	{ 0x6, 14 },
> > +	{ 0x7, 16 },
> > +	{ 0 }
> > +};
> > +
> > +static const struct clk_div_table ast2600_sd_div_a2_table[] = {
> > +	{ 0x0, 2 },
> > +	{ 0x1, 4 },
> > +	{ 0x2, 6 },
> > +	{ 0x3, 8 },
> > +	{ 0x4, 10 },
> > +	{ 0x5, 12 },
> > +	{ 0x6, 14 },
> > +	{ 0x7, 1 },
> > +	{ 0 }
> > +};
> > +
> >   /* For hpll/dpll/epll/mpll */
> >   static struct clk_hw *ast2600_calc_pll(const char *name, u32 val)
> >   {
> > @@ -424,6 +448,11 @@ static const char *const
> emmc_extclk_parent_names[] = {
> >   	"mpll",
> >   };
> >
> > +static const char *const sd_extclk_parent_names[] = {
> > +	"hclk",
> > +	"apll",
> > +};
> > +
> >   static const char * const vclk_parent_names[] = {
> >   	"dpll",
> >   	"d1pll",
> > @@ -523,18 +552,42 @@ static int aspeed_g6_clk_probe(struct
> platform_device *pdev)
> >   		return PTR_ERR(hw);
> >   	aspeed_g6_clk_data->hws[ASPEED_CLK_EMMC] = hw;
> >
> > -	/* SD/SDIO clock divider and gate */
> > -	hw = clk_hw_register_gate(dev, "sd_extclk_gate", "hpll", 0,
> > -			scu_g6_base + ASPEED_G6_CLK_SELECTION4, 31, 0,
> > -			&aspeed_g6_clk_lock);
> > +	clk_hw_register_fixed_rate(NULL, "hclk", NULL, 0, 200000000);
> > +
> > +	regmap_read(map, 0x310, &val);
> > +	hw = clk_hw_register_mux(dev, "sd_extclk_mux",
> > +				 sd_extclk_parent_names,
> > +				 ARRAY_SIZE(sd_extclk_parent_names), 0,
> > +				 scu_g6_base + ASPEED_G6_CLK_SELECTION4, 8, 1,
> > +				 0, &aspeed_g6_clk_lock);
> >   	if (IS_ERR(hw))
> >   		return PTR_ERR(hw);
> > -	hw = clk_hw_register_divider_table(dev, "sd_extclk", "sd_extclk_gate",
> > -			0, scu_g6_base + ASPEED_G6_CLK_SELECTION4, 28, 3, 0,
> > -			ast2600_div_table,
> > -			&aspeed_g6_clk_lock);
> > +
> > +	hw = clk_hw_register_gate(dev, "sd_extclk_gate", "sd_extclk_mux",
> > +				  0, scu_g6_base + ASPEED_G6_CLK_SELECTION4,
> > +				  31, 0, &aspeed_g6_clk_lock);
> >   	if (IS_ERR(hw))
> >   		return PTR_ERR(hw);
> > +
> > +	regmap_read(map, 0x14, &val);
> > +	/* AST2600-A2/A3 clock divisor is different from AST2600-A1 */
> > +	if (((val & GENMASK(23, 16)) >> 16) >= 2) {
> > +		/* AST2600-A2/A3 */
> > +		hw = clk_hw_register_divider_table(dev, "sd_extclk",
> "sd_extclk_gate",
> > +					0, scu_g6_base + ASPEED_G6_CLK_SELECTION4, 28, 3,
> 0,
> > +					ast2600_sd_div_a2_table,
> > +					&aspeed_g6_clk_lock);
> > +		if (IS_ERR(hw))
> > +			return PTR_ERR(hw);
> > +	} else {
> > +		/* AST2600-A1 */
> > +		hw = clk_hw_register_divider_table(dev, "sd_extclk",
> "sd_extclk_gate",
> > +					0, scu_g6_base + ASPEED_G6_CLK_SELECTION4, 28, 3,
> 0,
> > +					ast2600_sd_div_a1_table,
> > +					&aspeed_g6_clk_lock);
> > +		if (IS_ERR(hw))
> > +			return PTR_ERR(hw);
> > +	}
> >   	aspeed_g6_clk_data->hws[ASPEED_CLK_SDIO] = hw;
> >
> >   	/* MAC1/2 RMII 50MHz RCLK */
> >
> 
> Does Linux already log, if A1 or A2/A3 is detected?
> 

No, but Joel provided a related patch for SoC version in clk-ast2600.c.

> Should a debug message be added, what clock divisor is used?
> 

Okay, the debug message for clock divisor will be added in the next patch version.

> 
> Kind regards,
> 
> Paul


Best Wishes,
Chin-Ting