Re: [U-Boot] [PATCH 4/6] sandbox: new SPI flash driver

Hi Mike,

On Sun, Jan 22, 2012 at 10:30 PM, Mike Frysinger vapier@gentoo.org wrote:

This adds a SPI flash driver which simulates SPI flash clients. Currently supports the bare min that U-Boot requires: you can probe, read, erase, and write.  Should be easy to extend to make it behave more exactly like a real SPI flash, but this is good enough to merge now.

Signed-off-by: Mike Frysinger vapier@gentoo.org

drivers/mtd/spi/Makefile  |    1 +  drivers/mtd/spi/sandbox.c |  318 +++++++++++++++++++++++++++++++++++++++++++++  drivers/spi/sandbox_spi.c |    5 +  3 files changed, 324 insertions(+), 0 deletions(-)  create mode 100644 drivers/mtd/spi/sandbox.c

Again would like a few comments / docs. I'm pleased you have done this - it is much more comprehensive than my noddy implementation.

diff --git a/drivers/mtd/spi/Makefile b/drivers/mtd/spi/Makefile index 90f8392..fb37807 100644 --- a/drivers/mtd/spi/Makefile +++ b/drivers/mtd/spi/Makefile @@ -33,6 +33,7 @@ COBJS-$(CONFIG_SPI_FLASH)     += spi_flash.o  COBJS-$(CONFIG_SPI_FLASH_ATMEL)        += atmel.o  COBJS-$(CONFIG_SPI_FLASH_EON)  += eon.o  COBJS-$(CONFIG_SPI_FLASH_MACRONIX)     += macronix.o +COBJS-$(CONFIG_SPI_FLASH_SANDBOX)      += sandbox.o  COBJS-$(CONFIG_SPI_FLASH_SPANSION)     += spansion.o  COBJS-$(CONFIG_SPI_FLASH_SST)  += sst.o  COBJS-$(CONFIG_SPI_FLASH_STMICRO)      += stmicro.o diff --git a/drivers/mtd/spi/sandbox.c b/drivers/mtd/spi/sandbox.c new file mode 100644 index 0000000..a1bb641 --- /dev/null +++ b/drivers/mtd/spi/sandbox.c @@ -0,0 +1,318 @@ +/*

• • Simulate a SPI flash
• • Copyright (c) 2011-2012 The Chromium OS Authors.
• • See file CREDITS for list of people who contributed to this
• • project.
• • Licensed under the GPL-2 or later.
• */

+#include <common.h> +#include <malloc.h> +#include <spi.h> +#include <os.h>

+#include <spi_flash.h> +#include "spi_flash_internal.h"

+#include <asm/spi.h>

These are the different commands, right?

+typedef enum {

• SF_CMD, SF_ID, SF_READ, SF_WRITE, SF_ERASE, SF_READ_STATUS, SF_WREN, SF_WRDI,

+} sb_sf_state;

+#define STAT_WIP       (1 << 0) +#define STAT_WEL       (1 << 1)

What are these? Status bus? If so, perhaps a comment for each?

+struct sb_spi_flash_erase_commands {

• u8 cmd;
• u32 size;

+}; +#define IDCODE_LEN 5 +#define MAX_ERASE_CMDS 2 +struct sb_spi_flash_data {

• const char *name;
• u8 idcode[IDCODE_LEN];
• u32 size;
• const struct sb_spi_flash_erase_commands erase_cmds[MAX_ERASE_CMDS];

+};

+struct sb_spi_flash {

• sb_sf_state state;
• uint off;
• const struct sb_spi_flash_data *data;
• int fd;
• u8 status;

+};

All of the above could do with some comments IMO...

+static const char *sb_sf_state_name(sb_sf_state state) +{

• static const char * const states[] = {
• "CMD", "ID", "READ", "WRITE", "ERASE", "READ_STATUS", "WREN", "WRDI",
• };

I wonder if it would be better to put this array up next to the enum?

• return states[state];

+}

These are the emulated devices I think.

+static const struct sb_spi_flash_data sb_sf_flashes[] = {

• {
• "M25P16", { 0x20, 0x20, 0x15 }, (2 * 1024 * 1024),
• {       /* erase commands */
• { 0xd8, (64 * 1024), }, /* sector */
• { 0xc7, (2 * 1024 * 1024), }, /* bulk */

Is <<10, <<20 better? Not sure.

• },
• },

+};

+static u8 sb_sf_0xff[0x10000];

Perhaps we should add an os_fputc() instead? Or perhaps write in smaller chunks?

+static int sb_sf_setup(void **priv, const char *spec) +{

• /* spec = idcode:file */
• struct sb_spi_flash *sbsf;
• const char *file;
• size_t i, len, idname_len;
• const struct sb_spi_flash_data *data;
• file = strchr(spec, ':');
• if (!file)
• goto error;
• idname_len = file - spec;
• ++file;
• for (i = 0; i < ARRAY_SIZE(sb_sf_flashes); ++i) {
• data = &sb_sf_flashes[i];
• len = strlen(data->name);
• if (idname_len != len)
• continue;
• if (!memcmp(spec, data->name, len))
• break;
• }
• if (i == ARRAY_SIZE(sb_sf_flashes)) {
• printf("sandbox_spi_flash: unknown flash '%*s'\n",
• (int)idname_len, file);
• goto error;
• }
• if (sb_sf_0xff[0] == 0x00)
• memset(sb_sf_0xff, 0xff, sizeof(sb_sf_0xff));
• sbsf = malloc(sizeof(*sbsf));
• if (!sbsf)
• goto error;
• sbsf->fd = os_open(file, 02);
• if (sbsf->fd == -1) {
• free(sbsf);
• goto error;
• }
• sbsf->state = SF_CMD;
• sbsf->data = data;
• *priv = sbsf;
• return 0;
• error:
• printf("sandbox_spi_flash: unable to parse client spec\n");

or out of memory or file would not open

• return 1;

+}

+static void sb_sf_free(void *priv) +{

• struct sb_spi_flash *sbsf = priv;
• os_close(sbsf->fd);
• free(sbsf);

+}

+static void sb_sf_cs_deactivate(void *priv) +{

• struct sb_spi_flash *sbsf = priv;
• /* CS is no longer being asserted, so reset state */
• sbsf->state = SF_CMD;

+}

+static int sb_sf_xfer(void *priv, const u8 *tx, u8 *rx,

• uint bytes)

+{

• struct sb_spi_flash *sbsf = priv;
• uint i, written = 0;
• debug("sb_sf: state:%x(%s) bytes:%u\n", sbsf->state,
• sb_sf_state_name(sbsf->state), bytes);
• if (sbsf->state == SF_CMD) {

I wonder if this if() could be split out as it makes the function very long. Might be hard if too many parameters though.

• sb_sf_state oldstate = sbsf->state;
• rx[written++] = 0;
• sb_spi_tristate(rx, 1);
• /*
• * XXX: we assume cmds that need addresses get them in one
• *      transfer rather than accumulating ... but u-boot
• *      doesn't care at all.
• */
• switch (tx[0]) {
• case CMD_READ_ID:
• sbsf->off = 0;
• sbsf->state = SF_ID;
• break;
• case CMD_PAGE_PROGRAM:
• /* XXX: check WEL in status */
• /*
• * XXX: need to handle exotic behavior:
• *      - unaligned addresses
• *      - too big of an address
• */
• sbsf->off = (tx[1] << 16) | (tx[2] << 8) | tx[3];
• os_lseek(sbsf->fd, sbsf->off, 0);
• written += 3;
• sb_spi_tristate(&rx[1], 3);
• sbsf->state = SF_WRITE;
• sbsf->status &= ~STAT_WEL;
• break;
• case CMD_READ_ARRAY_SLOW:
• case CMD_READ_ARRAY_FAST: {
• uint alen = 3;
• sbsf->off = (tx[1] << 16) | (tx[2] << 8) | tx[3];
• os_lseek(sbsf->fd, sbsf->off, 0);
• debug(" read addr: %u\n", sbsf->off);
• if (tx[0] == CMD_READ_ARRAY_FAST)
• /* read fast needs a dummy byte */
• ++alen;
• written += alen;
• sb_spi_tristate(&rx[1], alen);
• sbsf->state = SF_READ;
• break;
• }

Are you allowed to not indent the {} in this case? The } ends up at the same level as the switch().

• case CMD_WRITE_DISABLE:
• debug(" write disabled\n");
• sbsf->status &= ~STAT_WEL;
• break;
• case CMD_READ_STATUS:
• sbsf->state = SF_READ_STATUS;
• break;
• case CMD_WRITE_ENABLE:
• debug(" write enabled\n");
• sbsf->status |= STAT_WEL;
• break;
• default:
• /* handle erase commands first */
• for (i = 0; i < MAX_ERASE_CMDS; ++i) {
• const struct sb_spi_flash_erase_commands *erase_cmd =
• &sbsf->data->erase_cmds[i];
• if (erase_cmd->cmd == 0x00)
• continue;
• if (tx[0] != erase_cmd->cmd)
• continue;
• /* XXX: check WEL in status */
• /* verify address is aligned */
• sbsf->off = (tx[1] << 16) | (tx[2] << 8) | tx[3];
• if (sbsf->off & ~(erase_cmd->size - 1)) {
• debug(" sector erase: cmd:%#x needs align:%#x, but we got %#x\n",
• erase_cmd->cmd, erase_cmd->size, sbsf->off);
• sbsf->status &= ~STAT_WEL;
• return 1;
• }
• os_lseek(sbsf->fd, sbsf->off, 0);
• debug(" sector erase addr: %u\n", sbsf->off);
• written += 3;
• sb_spi_tristate(&rx[1], 3);
• /* XXX: latch WIP in status, and delay before clearing it ? */
• os_write(sbsf->fd, sb_sf_0xff, erase_cmd->size);
• sbsf->status &= ~STAT_WEL;
• goto cmd_done;
• }
• debug(" cmd unknown: %#x\n", tx[0]);
• return 1;
• }
• cmd_done:
• if (oldstate != sbsf->state)
• debug(" cmd: transition to %s state\n",
• sb_sf_state_name(sbsf->state));
• }
• if (written == bytes)
• return 0;
• switch (sbsf->state) {
• case SF_ID: {
• const u8 *idcode = sbsf->data->idcode;
• debug(" id: off:%u\n tx:", sbsf->off);
• for (i = sbsf->off; i < IDCODE_LEN; ++i) {
• if (written < bytes) {
• rx[written++] = idcode[i];
• debug(" %02x", idcode[i]);
• } else
• break;
• }
• if (written < bytes) {
• i = bytes - written;

Do you think you should use a different variable than i in this case and below? I doubt it would affect the code output.

• debug(" <memset remaining %u bytes>", i);
• memset(rx + written, 0, i);
• written += i;
• }
• debug("\n");
• break;
• }
• case SF_READ:
• /*
• * XXX: need to handle exotic behavior:
• *      - reading past end of device
• */
• i = bytes - written;
• debug(" tx: read(%u)\n", i);
• if (i)
• written += os_read(sbsf->fd, rx + written, i);
• break;
• case SF_READ_STATUS:
• debug(" read status: %#x\n", sbsf->status);
• i = bytes - written;
• memset(rx + written, sbsf->status, i);
• written += i;
• break;
• case SF_WRITE:
• /*
• * XXX: need to handle exotic behavior:
• *      - more than a page (256) worth of data
• *      - reading past end of device
• */
• i = bytes - written;
• debug(" rx: write(%u)\n", i);
• if (i)
• written += os_write(sbsf->fd, tx + written, i);
• break;
• default:
• debug(" ??? no idea what to do ???\n");
• break;
• }
• return written == bytes ? 0 : 1;

+}

+const struct sb_spi_emu_ops sb_sf_ops = {

• .setup         = sb_sf_setup,
• .free          = sb_sf_free,
• .cs_deactivate = sb_sf_cs_deactivate,
• .xfer          = sb_sf_xfer,

+}; diff --git a/drivers/spi/sandbox_spi.c b/drivers/spi/sandbox_spi.c index eda0f3e..ae15946 100644 --- a/drivers/spi/sandbox_spi.c +++ b/drivers/spi/sandbox_spi.c @@ -35,10 +35,15 @@ static const char *sb_lookup_arg(unsigned int bus, unsigned int cs)        return os_getopt(sf_arg, 1);  }

+extern const struct sb_spi_emu_ops sb_sf_ops;

static const struct {        const char *spec;        const struct sb_spi_emu_ops *ops;  } sb_emu_map[] = { +#ifdef CONFIG_SPI_FLASH_SANDBOX

• { "sf", &sb_sf_ops, },

+#endif  };

static int sb_parse_type(struct sb_spi_slave *sss)

1.7.8.3

Regards, Simon