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

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@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@jcrosoft.com
• Copyright (C) 2013 Bo Shen voice.shen@atmel.com

• • Copyright (C) 2015 Wenyou Yang wenyou.yang@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