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 clock source of the GCK is fixed to PLLA_CLK.
Signed-off-by: Wenyou Yang wenyou.yang@atmel.com --- Hi Andreas, Bo Shen,
Thank you for your so many advices. Bo Shen, sorry for forgetting version 2 to send for your comments.
Please help review, thank you in advance.
Best Regards, Wenyou Yang
Changes in v2: 1./ add timeout to wait for GCK ready. 2./ add warning for timeout to wait for GCK ready. 3./ add printout when the improper GCK clock source is selected. 4./ rework AT91_PMC_PCR_GCKDIV_(x) macro to make sure x is right.
arch/arm/mach-at91/armv7/clock.c | 65 ++++++++++++++++++++++++++++ arch/arm/mach-at91/include/mach/at91_pmc.h | 13 ++++++ arch/arm/mach-at91/include/mach/clk.h | 3 ++ 3 files changed, 81 insertions(+)
diff --git a/arch/arm/mach-at91/armv7/clock.c b/arch/arm/mach-at91/armv7/clock.c index 0bf453e..de95d6b 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 +174,67 @@ 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, status; + u32 timeout = 1000; + + 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); + + do { + udelay(1); + status = readl(&pmc->sr); + } while ((!!(--timeout)) && (!(status & AT91_PMC_GCKRDY))); + + if (!timeout) + printf("Timeout waiting for GCK ready!\n"); +} + +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; + + 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: + printf("Improper GCK clock source selection!\n"); + freq = 0; + break; + } + + 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..5a51be6 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 & 0xff) << 20) +#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__ */