From f568880f8f560938650896284950338592d0f8fa Mon Sep 17 00:00:00 2001 From: Hubert Feurstein Date: Mon, 20 Jun 2011 23:46:34 +0200 Subject: eeprom: add at25 eeprom driver This commit adds support for most spi eeproms, such as the Atmel at25 models. Signed-off-by: Hubert Feurstein Signed-off-by: Sascha Hauer --- drivers/Kconfig | 1 + drivers/Makefile | 1 + drivers/eeprom/Kconfig | 11 ++ drivers/eeprom/Makefile | 1 + drivers/eeprom/at25.c | 319 ++++++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 333 insertions(+) create mode 100644 drivers/eeprom/Kconfig create mode 100644 drivers/eeprom/Makefile create mode 100644 drivers/eeprom/at25.c (limited to 'drivers') diff --git a/drivers/Kconfig b/drivers/Kconfig index 86d8fb54cc..c4e1517ca6 100644 --- a/drivers/Kconfig +++ b/drivers/Kconfig @@ -13,5 +13,6 @@ source "drivers/mci/Kconfig" source "drivers/clk/Kconfig" source "drivers/mfd/Kconfig" source "drivers/led/Kconfig" +source "drivers/eeprom/Kconfig" endmenu diff --git a/drivers/Makefile b/drivers/Makefile index b1b402fb49..92b22bdaa9 100644 --- a/drivers/Makefile +++ b/drivers/Makefile @@ -11,3 +11,4 @@ obj-$(CONFIG_VIDEO) += video/ obj-y += clk/ obj-y += mfd/ obj-$(CONFIG_LED) += led/ +obj-y += eeprom/ diff --git a/drivers/eeprom/Kconfig b/drivers/eeprom/Kconfig new file mode 100644 index 0000000000..a0b54899c6 --- /dev/null +++ b/drivers/eeprom/Kconfig @@ -0,0 +1,11 @@ +menu "EEPROM support" + +config EEPROM_AT25 + tristate "SPI EEPROMs from most vendors" + depends on SPI + help + Enable this driver to get read/write support to most SPI EEPROMs, + after you configure the board init code to know about each eeprom + on your target board. + +endmenu diff --git a/drivers/eeprom/Makefile b/drivers/eeprom/Makefile new file mode 100644 index 0000000000..e323bd0caf --- /dev/null +++ b/drivers/eeprom/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_EEPROM_AT25) += at25.o diff --git a/drivers/eeprom/at25.c b/drivers/eeprom/at25.c new file mode 100644 index 0000000000..8a979d53a1 --- /dev/null +++ b/drivers/eeprom/at25.c @@ -0,0 +1,319 @@ +/* + * at25.c -- support most SPI EEPROMs, such as Atmel AT25 models + * + * Copyright (C) 2011 Hubert Feurstein + * + * based on linux driver by: + * Copyright (C) 2006 David Brownell + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * NOTE: this is an *EEPROM* driver. The vagaries of product naming + * mean that some AT25 products are EEPROMs, and others are FLASH. + * Handle FLASH chips with the drivers/mtd/devices/m25p80.c driver, + * not this one! + */ + +struct at25_data { + struct cdev cdev; + struct spi_device *spi; + struct spi_eeprom chip; + unsigned addrlen; +}; + +#define to_at25_data(cdev) ((struct at25_data *)(cdev)->priv) + +#define AT25_WREN 0x06 /* latch the write enable */ +#define AT25_WRDI 0x04 /* reset the write enable */ +#define AT25_RDSR 0x05 /* read status register */ +#define AT25_WRSR 0x01 /* write status register */ +#define AT25_READ 0x03 /* read byte(s) */ +#define AT25_WRITE 0x02 /* write byte(s)/sector */ + +#define AT25_SR_nRDY 0x01 /* nRDY = write-in-progress */ +#define AT25_SR_WEN 0x02 /* write enable (latched) */ +#define AT25_SR_BP0 0x04 /* BP for software writeprotect */ +#define AT25_SR_BP1 0x08 +#define AT25_SR_WPEN 0x80 /* writeprotect enable */ + + +#define EE_MAXADDRLEN 3 /* 24 bit addresses, up to 2 MBytes */ + +/* Specs often allow 5 msec for a page write, sometimes 20 msec; + * it's important to recover from write timeouts. + */ +#define EE_TIMEOUT (25 * MSECOND) +#define DRIVERNAME "at25x" + +/*-------------------------------------------------------------------------*/ + +#define io_limit PAGE_SIZE /* bytes */ + +static ssize_t at25_ee_read(struct cdev *cdev, + void *buf, + size_t count, + ulong offset, + ulong flags) +{ + u8 command[EE_MAXADDRLEN + 1]; + u8 *cp; + ssize_t status; + struct spi_transfer t[2]; + struct spi_message m; + struct at25_data *at25 = to_at25_data(cdev); + + if (unlikely(offset >= at25->chip.size)) + return 0; + if ((offset + count) > at25->chip.size) + count = at25->chip.size - offset; + if (unlikely(!count)) + return count; + + cp = command; + *cp++ = AT25_READ; + + /* 8/16/24-bit address is written MSB first */ + switch (at25->addrlen) { + default: /* case 3 */ + *cp++ = offset >> 16; + case 2: + *cp++ = offset >> 8; + case 1: + case 0: /* can't happen: for better codegen */ + *cp++ = offset >> 0; + } + + spi_message_init(&m); + memset(t, 0, sizeof t); + + t[0].tx_buf = command; + t[0].len = at25->addrlen + 1; + spi_message_add_tail(&t[0], &m); + + t[1].rx_buf = buf; + t[1].len = count; + spi_message_add_tail(&t[1], &m); + + /* Read it all at once. + * + * REVISIT that's potentially a problem with large chips, if + * other devices on the bus need to be accessed regularly or + * this chip is clocked very slowly + */ + status = spi_sync(at25->spi, &m); + dev_dbg(at25->cdev.dev, + "read %d bytes at %lu --> %d\n", + count, offset, (int) status); + + return status ? status : count; +} + +static ssize_t at25_ee_write(struct cdev *cdev, + const void *buf, + size_t count, + ulong off, + ulong flags) +{ + ssize_t status = 0; + unsigned written = 0; + unsigned buf_size; + u8 *bounce; + struct at25_data *at25 = to_at25_data(cdev); + + if (unlikely(off >= at25->chip.size)) + return -EFBIG; + if ((off + count) > at25->chip.size) + count = at25->chip.size - off; + if (unlikely(!count)) + return count; + + /* Temp buffer starts with command and address */ + buf_size = at25->chip.page_size; + if (buf_size > io_limit) + buf_size = io_limit; + bounce = xmalloc(buf_size + at25->addrlen + 1); + + /* For write, rollover is within the page ... so we write at + * most one page, then manually roll over to the next page. + */ + bounce[0] = AT25_WRITE; + + do { + uint64_t start_time; + unsigned segment; + unsigned offset = (unsigned) off; + u8 *cp = bounce + 1; + int sr; + + *cp = AT25_WREN; + status = spi_write(at25->spi, cp, 1); + if (status < 0) { + dev_dbg(at25->cdev.dev, "WREN --> %d\n", + (int) status); + break; + } + + /* 8/16/24-bit address is written MSB first */ + switch (at25->addrlen) { + default: /* case 3 */ + *cp++ = offset >> 16; + case 2: + *cp++ = offset >> 8; + case 1: + case 0: /* can't happen: for better codegen */ + *cp++ = offset >> 0; + } + + /* Write as much of a page as we can */ + segment = buf_size - (offset % buf_size); + if (segment > count) + segment = count; + memcpy(cp, buf, segment); + status = spi_write(at25->spi, bounce, + segment + at25->addrlen + 1); + dev_dbg(at25->cdev.dev, + "write %u bytes at %u --> %d\n", + segment, offset, (int) status); + if (status < 0) + break; + + /* REVISIT this should detect (or prevent) failed writes + * to readonly sections of the EEPROM... + */ + + /* Wait for non-busy status */ + start_time = get_time_ns(); + + do { + sr = spi_w8r8(at25->spi, AT25_RDSR); + if (sr < 0 || (sr & AT25_SR_nRDY)) { + dev_dbg(at25->cdev.dev, + "rdsr --> %d (%02x)\n", sr, sr); + continue; + } + if (!(sr & AT25_SR_nRDY)) + break; + } while (!is_timeout(start_time, EE_TIMEOUT)); + + if ((sr < 0) || (sr & AT25_SR_nRDY)) { + dev_err(at25->cdev.dev, + "write %d bytes offset %d, " + "timeout after %u msecs\n", + segment, offset, + (unsigned int)(get_time_ns() - start_time) / + 1000000); + status = -ETIMEDOUT; + break; + } + + off += segment; + buf += segment; + count -= segment; + written += segment; + + } while (count > 0); + + free(bounce); + return written ? written : status; +} + +static off_t at25_ee_lseek(struct cdev *cdev, off_t off) +{ + return off; +} + +static struct file_operations at25_fops = { + .read = at25_ee_read, + .write = at25_ee_write, + .lseek = at25_ee_lseek, +}; + +static int at25_probe(struct device_d *dev) +{ + int err, sr; + int addrlen; + struct at25_data *at25 = NULL; + const struct spi_eeprom *chip; + + /* Chip description */ + chip = dev->platform_data; + if (!chip) { + dev_dbg(dev, "no chip description\n"); + err = -ENODEV; + goto fail; + } + + /* For now we only support 8/16/24 bit addressing */ + if (chip->flags & EE_ADDR1) { + addrlen = 1; + } else if (chip->flags & EE_ADDR2) { + addrlen = 2; + } else if (chip->flags & EE_ADDR3) { + addrlen = 3; + } else { + dev_dbg(dev, "unsupported address type\n"); + err = -EINVAL; + goto fail; + } + + at25 = xzalloc(sizeof(*at25)); + at25->chip = *chip; + at25->addrlen = addrlen; + at25->spi = dev->type_data; + at25->spi->mode = SPI_MODE_0; + at25->spi->bits_per_word = 8; + at25->cdev.ops = &at25_fops; + at25->cdev.size = chip->size; + at25->cdev.dev = dev; + at25->cdev.name = at25->chip.name[0] ? at25->chip.name : DRIVERNAME; + at25->cdev.priv = at25; + + /* Ping the chip ... the status register is pretty portable, + * unlike probing manufacturer IDs. We do expect that system + * firmware didn't write it in the past few milliseconds! + */ + sr = spi_w8r8(at25->spi, AT25_RDSR); + if (sr < 0 || sr & AT25_SR_nRDY) { + dev_dbg(dev, "rdsr --> %d (%02x)\n", sr, sr); + err = -ENXIO; + goto fail; + } + + dev_dbg(dev, "%s probed\n", at25->cdev.name); + devfs_create(&at25->cdev); + return 0; + +fail: + if (at25) + free(at25); + + return err; +} + +static struct driver_d at25_driver = { + .name = DRIVERNAME, + .probe = at25_probe, +}; + +static int at25_init(void) +{ + register_driver(&at25_driver); + return 0; +} + +device_initcall(at25_init); -- cgit v1.2.3