From mboxrd@z Thu Jan 1 00:00:00 1970 From: Valentin Longchamp Date: Tue, 14 Aug 2012 11:32:11 +0200 Subject: [U-Boot] [PATCH] kw_spi: fix clock prescaler computation In-Reply-To: <1340972242-24360-1-git-send-email-valentin.longchamp@keymile.com> References: <1340972242-24360-1-git-send-email-valentin.longchamp@keymile.com> Message-ID: <502A1B1B.5020802@keymile.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Prafulla, I haven't received feedback about this patch from you. Can I please kindly remind you about it since I am about to send patches that deal with SPI clk setting. Thank you. On 06/29/2012 02:17 PM, Valentin Longchamp wrote: > The computation was not correct with low clock values: setting a 1MHz > clock would result in an overlap that would then configure a 25Mhz > clock. > > This patch implements a correct computation method according to the > kirkwood functionnal spec. table 629 (Serial Memory Interface > Configuration Register). > > Signed-off-by: Valentin Longchamp > cc: Holger Brunck > cc: Prafulla Wadaskar > --- > arch/arm/include/asm/arch-kirkwood/spi.h | 1 + > drivers/spi/kirkwood_spi.c | 5 +++-- > 2 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/include/asm/arch-kirkwood/spi.h b/arch/arm/include/asm/arch-kirkwood/spi.h > index 1d5043f..5a38dc5 100644 > --- a/arch/arm/include/asm/arch-kirkwood/spi.h > +++ b/arch/arm/include/asm/arch-kirkwood/spi.h > @@ -38,6 +38,7 @@ struct kwspi_registers { > }; > > #define KWSPI_CLKPRESCL_MASK 0x1f > +#define KWSPI_CLKPRESCL_MIN 0x12 > #define KWSPI_CSN_ACT 1 /* Activates serial memory interface */ > #define KWSPI_SMEMRDY (1 << 1) /* SerMem Data xfer ready */ > #define KWSPI_IRQUNMASK 1 /* unmask SPI interrupt */ > diff --git a/drivers/spi/kirkwood_spi.c b/drivers/spi/kirkwood_spi.c > index ee14669..9b3f6a4 100644 > --- a/drivers/spi/kirkwood_spi.c > +++ b/drivers/spi/kirkwood_spi.c > @@ -57,8 +57,9 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, > writel(~KWSPI_CSN_ACT | KWSPI_SMEMRDY, &spireg->ctrl); > > /* calculate spi clock prescaller using max_hz */ > - data = ((CONFIG_SYS_TCLK / 2) / max_hz) & KWSPI_CLKPRESCL_MASK; > - data |= 0x10; > + data = ((CONFIG_SYS_TCLK / 2) / max_hz) + 0x10; > + data = data < KWSPI_CLKPRESCL_MIN ? KWSPI_CLKPRESCL_MIN : data; > + data = data > KWSPI_CLKPRESCL_MASK ? KWSPI_CLKPRESCL_MASK : data; > > /* program spi clock prescaller using max_hz */ > writel(KWSPI_ADRLEN_3BYTE | data, &spireg->cfg); >