SPI trouble on Colibri 270 (PXA)...

[Eric Miao]

On Tue, Apr 20, 2010 at 7:58 PM, Jakob Viketoft <jakob at viketoft.se> wrote:
> Hello!
>
> I've come to a dead end in finding out what's wrong with my SPI setup so I
> was hoping that someone here has some pointers to help me along. I'm trying
> to use an m25p80 SPI flash through the pxa2xx SPI controller (through SSP1),
> but read accesses go wrong (I haven't even tried writing yet). What happens
> is that after the pxa2xx writes the read command on the SPI bus, the chip is
> deselected - effectively terminating the read operation. Some 100 us
> afterwards the cs go low again and it seems as the read operation is
> continued (clock runs, no output data), but by then the chip has already
> terminated. Forcing the cs_change bit on each transfer doesn't seem to do
> any difference, there is still a pause between two transfers in the same
> message.
>
> I haven't seen any other board using the same combination (the m25p80 and
> the pxa2xx), but I'm still opting for an error on my part somewhere. I've
> attached my SPI configuration (board setup) in the end of the mail.
>

Not looked into m25p80 code, but CS is normally asserted before a transfer
begins and deasserted after a transfer is done. I doubt there are some cases
where the transfer is not set up correctly.

Actually, cs_assert() and cs_deassert() are there in pxa2xx_spi.c as two very
good debugging point to print out the transfer information to see if they are
setup correctly.

> I'm ready for any suggestions at this point. Please CC me as I'm not on the
> list.
>
> Regards,
>
>        /Jakob
>
> ------------
>
> /*
>  *  linux/arch/arm/mach-pxa/colibri-pxa270-spi.c
>  *
>  *  Separate file for the Toradex Colibri 270 SPI definitions to avoid
>  *  conflicts with the "regular" flash includes.
>  *  Jakob Viketoft <info at bitsim.com>
>  *
>  *  This program is free software; you can redistribute it and/or modify
>  *  it under the terms of the GNU General Public License version 2 as
>  *  published by the Free Software Foundation.
>  */
>
> #include <linux/mtd/mtd.h>
> #include <linux/mtd/partitions.h>
> #include <linux/mtd/physmap.h>
> #include <linux/spi/spi.h>
> #include <linux/spi/flash.h>
> #include <mach/pxa2xx_spi.h>
> #include <mach/mfp-pxa27x.h>
> #include <mach/pxa2xx-regs.h>
> #include <mach/gpio.h>
>
> #include "generic.h"
> #include "devices.h"
>
> /* SPI interface on SSP1 */
> static unsigned long colibri_spi_pin_config[] __initdata = {
>        GPIO23_SSP1_SCLK,
>        GPIO24_SSP1_SFRM,
>        GPIO25_SSP1_TXD,
>        GPIO26_SSP1_RXD,
> };
>
> static struct pxa2xx_spi_master colibri_spi_ssp1_info = {
>        .clock_enable = CKEN_SSP1,
>        .num_chipselect = 1,
>        .enable_dma = 0,
> };
>
> struct mtd_partition fpga_flash_partitions[] = {
>        {
>                .name           = "FPGA code",
>                .size           = 0x00100000,
>                .offset         = 0,
>                .mask_flags     = 0,
> //              .mask_flags     = MTD_WRITEABLE,
>        },
> };
>
> static struct flash_platform_data colibri_spi_m25p80_info = {
>        .type           = "m25p80",
>        .name           = "fpga_flash",
>        .parts          = fpga_flash_partitions,
>        .nr_parts       = ARRAY_SIZE(fpga_flash_partitions),
> };
>
> static struct pxa2xx_spi_chip colibri_spi_m25p80_chip = {
>        .rx_threshold = 1,
>        .tx_threshold = 1,
>        .gpio_cs = GPIO24_SSP1_SFRM,
> };
>
> static struct spi_board_info __initdata colibri_spi_devices[] = {
>        {
>                .modalias       = "m25p80",
>                .max_speed_hz   = 1200000,
>                .bus_num        = 1,
>                .chip_select    = 0,
>                .platform_data  = &colibri_spi_m25p80_info,
>                .controller_data= &colibri_spi_m25p80_chip,
>        },
>  };
>
> static int __init colibri_init_spi(void)
> {
>        printk(KERN_ERR "Init Colibri SPI\n");
>        pxa2xx_mfp_config(ARRAY_AND_SIZE(colibri_spi_pin_config));
>        pxa2xx_set_spi_info(1, &colibri_spi_ssp1_info);
>        return spi_register_board_info(ARRAY_AND_SIZE(colibri_spi_devices));
> }
>
> subsys_initcall(colibri_init_spi);
>
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