As said in 29.5.7 section of SAMA5D2 datasheet, before switching to the crystal oscillator, a check must be carried out to ensure that the oscillator is present and that its freqency is valid.
Signed-off-by: Wenyou Yang wenyou.yang@microchip.com ---
arch/arm/mach-at91/include/mach/at91_pmc.h | 2 ++ arch/arm/mach-at91/spl_atmel.c | 18 +++++++++++++++++- 2 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mach-at91/include/mach/at91_pmc.h b/arch/arm/mach-at91/include/mach/at91_pmc.h index 2875ff20b1..08ad1bf2d0 100644 --- a/arch/arm/mach-at91/include/mach/at91_pmc.h +++ b/arch/arm/mach-at91/include/mach/at91_pmc.h @@ -87,6 +87,8 @@ typedef struct at91_pmc {
#define AT91_PMC_MCFR_MAINRDY 0x00010000 #define AT91_PMC_MCFR_MAINF_MASK 0x0000FFFF +#define AT91_PMC_MCFR_RCMEAS 0x00100000 +#define AT91_PMC_MCFR_CCSS_XTAL_OSC 0x01000000
#define AT91_PMC_MCKR_CSS_SLOW 0x00000000 #define AT91_PMC_MCKR_CSS_MAIN 0x00000001 diff --git a/arch/arm/mach-at91/spl_atmel.c b/arch/arm/mach-at91/spl_atmel.c index b75c2ccefd..ce16ef3bdb 100644 --- a/arch/arm/mach-at91/spl_atmel.c +++ b/arch/arm/mach-at91/spl_atmel.c @@ -32,6 +32,20 @@ static void switch_to_main_crystal_osc(void) while (!(readl(&pmc->sr) & AT91_PMC_IXR_MOSCS)) ;
+#if defined(CONFIG_SAMA5D2) + /* Enable a measurement of the external oscillator */ + tmp = readl(&pmc->mcfr); + tmp |= AT91_PMC_MCFR_CCSS_XTAL_OSC; + tmp |= AT91_PMC_MCFR_RCMEAS; + writel(tmp, &pmc->mcfr); + + while (!(readl(&pmc->mcfr) & AT91_PMC_MCFR_MAINRDY)) + ; + + if (!(readl(&pmc->mcfr) & AT91_PMC_MCFR_MAINF_MASK)) + hang(); +#endif + tmp = readl(&pmc->mor); tmp &= ~AT91_PMC_MOR_OSCBYPASS; tmp &= ~AT91_PMC_MOR_KEY(0xff); @@ -47,11 +61,13 @@ static void switch_to_main_crystal_osc(void) while (!(readl(&pmc->sr) & AT91_PMC_IXR_MOSCSELS)) ;
+#if !defined(CONFIG_SAMA5D2) /* Wait until MAINRDY field is set to make sure main clock is stable */ while (!(readl(&pmc->mcfr) & AT91_PMC_MAINRDY)) ; +#endif
-#ifndef CONFIG_SAMA5D4 +#if !defined(CONFIG_SAMA5D4) && !defined(CONFIG_SAMA5D2) tmp = readl(&pmc->mor); tmp &= ~AT91_PMC_MOR_MOSCRCEN; tmp &= ~AT91_PMC_MOR_KEY(0xff);