[U-Boot] [PATCH] arm: at91: clock: Add the generated clock support

[Bo Shen]

Hi Wenyou,

On 09/09/2015 10:29 AM, Wenyou Yang wrote:
> Some peripherals may need a second clock source that may be different
> from the system clock. This second clock is the generated clock (GCK)
> and is managed by the PMC via PMC_PCR.
>
> For simplicity, the source of the GCK is fixed to PLLA_CLK.
>
> Signed-off-by: Wenyou Yang <wenyou.yang at atmel.com>
> ---
>
>   arch/arm/mach-at91/armv7/clock.c           |   57 ++++++++++++++++++++++++++++
>   arch/arm/mach-at91/include/mach/at91_pmc.h |   13 +++++++
>   arch/arm/mach-at91/include/mach/clk.h      |    3 ++
>   3 files changed, 73 insertions(+)
>
> diff --git a/arch/arm/mach-at91/armv7/clock.c b/arch/arm/mach-at91/armv7/clock.c
> index 0bf453e..84418a3 100644
> --- a/arch/arm/mach-at91/armv7/clock.c
> +++ b/arch/arm/mach-at91/armv7/clock.c
> @@ -5,6 +5,7 @@
>    * Copyright (C) 2005 Ivan Kokshaysky
>    * Copyright (C) 2009 Jean-Christophe PLAGNIOL-VILLARD <plagnioj at jcrosoft.com>
>    * Copyright (C) 2013 Bo Shen <voice.shen at atmel.com>
> + * Copyright (C) 2015 Wenyou Yang <wenyou.yang at atmel.com>
>    *
>    * SPDX-License-Identifier:	GPL-2.0+
>    */
> @@ -173,3 +174,59 @@ void at91_periph_clk_disable(int id)
>
>   	writel(regval, &pmc->pcr);
>   }
> +
> +void at91_enable_periph_generated_clk(u32 id)
> +{
> +	struct at91_pmc *pmc = (struct at91_pmc *)ATMEL_BASE_PMC;
> +	u32 regval;
> +
> +	if (id > AT91_PMC_PCR_PID_MASK)
> +		return;
> +
> +	writel(id, &pmc->pcr);
> +	regval = readl(&pmc->pcr);
> +	regval &= ~AT91_PMC_PCR_GCKCSS;
> +	regval &= ~AT91_PMC_PCR_GCKDIV;
> +	regval |= AT91_PMC_PCR_GCKCSS_PLLA_CLK |
> +		  AT91_PMC_PCR_CMD_WRITE |
> +		  AT91_PMC_PCR_GCKDIV_(1) |
> +		  AT91_PMC_PCR_GCKEN;
> +
> +	writel(regval, &pmc->pcr);
> +
> +	while (!(readl(&pmc->sr) & AT91_PMC_GCKRDY))
> +		;

Here, do we need to hang the whole system?

> +}
> +
> +u32 at91_get_periph_generated_clk(u32 id)
> +{
> +	struct at91_pmc *pmc = (struct at91_pmc *)ATMEL_BASE_PMC;
> +	u32 regval, clk_source, div;
> +	u32 freq = 0;
> +
> +	if (id > AT91_PMC_PCR_PID_MASK)
> +		return 0;
> +
> +	writel(id, &pmc->pcr);
> +	regval = readl(&pmc->pcr);
> +
> +	clk_source = regval & AT91_PMC_PCR_GCKCSS;
> +	switch (clk_source) {
> +	case AT91_PMC_PCR_GCKCSS_SLOW_CLK:
> +		freq = CONFIG_SYS_AT91_SLOW_CLOCK;
> +		break;
> +	case AT91_PMC_PCR_GCKCSS_MAIN_CLK:
> +		freq = gd->arch.main_clk_rate_hz;
> +		break;
> +	case AT91_PMC_PCR_GCKCSS_PLLA_CLK:
> +		freq = gd->arch.plla_rate_hz;
> +		break;
> +	default:
> +		break;

For the default, is it valuable to add error information? Or return an 
invalid value?

> +	}
> +
> +	div = ((regval & AT91_PMC_PCR_GCKDIV) >> AT91_PMC_PCR_GCKDIV_OFFSET);
> +	div += 1;
> +
> +	return freq / div;
> +}
> diff --git a/arch/arm/mach-at91/include/mach/at91_pmc.h b/arch/arm/mach-at91/include/mach/at91_pmc.h
> index 8a3fb94..dcd6e36 100644
> --- a/arch/arm/mach-at91/include/mach/at91_pmc.h
> +++ b/arch/arm/mach-at91/include/mach/at91_pmc.h
> @@ -153,8 +153,20 @@ typedef struct at91_pmc {
>   #define AT91_PMC_IXR_MOSCSELS		0x00010000
>
>   #define AT91_PMC_PCR_PID_MASK		(0x3f)
> +#define AT91_PMC_PCR_GCKCSS		(0x7 << 8)
> +#define		AT91_PMC_PCR_GCKCSS_SLOW_CLK	(0x0 << 8)
> +#define		AT91_PMC_PCR_GCKCSS_MAIN_CLK	(0x1 << 8)
> +#define		AT91_PMC_PCR_GCKCSS_PLLA_CLK	(0x2 << 8)
> +#define		AT91_PMC_PCR_GCKCSS_UPLL_CLK	(0x3 << 8)
> +#define		AT91_PMC_PCR_GCKCSS_MCK_CLK	(0x4 << 8)
> +#define		AT91_PMC_PCR_GCKCSS_AUDIO_CLK	(0x5 << 8)
>   #define AT91_PMC_PCR_CMD_WRITE		(0x1 << 12)
> +#define AT91_PMC_PCR_DIV		(0x3 << 16)
> +#define AT91_PMC_PCR_GCKDIV		(0xff << 20)
> +#define		AT91_PMC_PCR_GCKDIV_(x)		((x) << 20)

It is dangerous here, if "x = 0xfff", then what will happen?

> +#define		AT91_PMC_PCR_GCKDIV_OFFSET	20
>   #define AT91_PMC_PCR_EN			(0x1 << 28)
> +#define AT91_PMC_PCR_GCKEN		(0x1 << 29)
>
>   #define		AT91_PMC_PCK		(1 <<  0)		/* Processor Clock */
>   #define		AT91RM9200_PMC_UDP	(1 <<  1)		/* USB Devcice Port Clock [AT91RM9200 only] */
> @@ -236,6 +248,7 @@ typedef struct at91_pmc {
>   #define		AT91_PMC_PCK1RDY	(1 <<  9)		/* Programmable Clock 1 */
>   #define		AT91_PMC_PCK2RDY	(1 << 10)		/* Programmable Clock 2 */
>   #define		AT91_PMC_PCK3RDY	(1 << 11)		/* Programmable Clock 3 */
> +#define		AT91_PMC_GCKRDY		(1 << 24)
>
>   #define		AT91_PMC_PROTKEY	0x504d4301	/* Activation Code */
>   #endif
> diff --git a/arch/arm/mach-at91/include/mach/clk.h b/arch/arm/mach-at91/include/mach/clk.h
> index 1d45e2d..dd1ed96 100644
> --- a/arch/arm/mach-at91/include/mach/clk.h
> +++ b/arch/arm/mach-at91/include/mach/clk.h
> @@ -119,4 +119,7 @@ static inline unsigned long get_pit_clk_rate(void)
>   int at91_clock_init(unsigned long main_clock);
>   void at91_periph_clk_enable(int id);
>   void at91_periph_clk_disable(int id);
> +void at91_enable_periph_generated_clk(u32 id);
> +u32 at91_get_periph_generated_clk(u32 id);
> +
>   #endif /* __ASM_ARM_ARCH_CLK_H__ */
>

Best Regards,
Bo Shen