diff options
| -rw-r--r-- | drivers/spi/Kconfig | 10 | ||||
| -rw-r--r-- | drivers/spi/Makefile | 1 | ||||
| -rw-r--r-- | drivers/spi/at25.c | 381 | ||||
| -rw-r--r-- | include/linux/spi/eeprom.h | 22 |
4 files changed, 414 insertions, 0 deletions
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig index b217a65453f..9052f4c3493 100644 --- a/drivers/spi/Kconfig +++ b/drivers/spi/Kconfig @@ -135,6 +135,16 @@ config SPI_S3C24XX_GPIO comment "SPI Protocol Masters" depends on SPI_MASTER +config SPI_AT25 + tristate "SPI EEPROMs from most vendors" + depends on SPI_MASTER && SYSFS + 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. + + This driver can also be built as a module. If so, the module + will be called at25. # # Add new SPI protocol masters in alphabetical order above this line diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile index e01104d1ebf..bf271fe4e53 100644 --- a/drivers/spi/Makefile +++ b/drivers/spi/Makefile @@ -22,6 +22,7 @@ obj-$(CONFIG_SPI_S3C24XX) += spi_s3c24xx.o # ... add above this line ... # SPI protocol drivers (device/link on bus) +obj-$(CONFIG_SPI_AT25) += at25.o # ... add above this line ... # SPI slave controller drivers (upstream link) diff --git a/drivers/spi/at25.c b/drivers/spi/at25.c new file mode 100644 index 00000000000..48e4f48e779 --- /dev/null +++ b/drivers/spi/at25.c @@ -0,0 +1,381 @@ +/* + * at25.c -- support most SPI EEPROMs, such as Atmel AT25 models + * + * 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 <linux/kernel.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/delay.h> +#include <linux/device.h> +#include <linux/sched.h> + +#include <linux/spi/spi.h> +#include <linux/spi/eeprom.h> + + +struct at25_data { + struct spi_device *spi; + struct mutex lock; + struct spi_eeprom chip; + struct bin_attribute bin; + unsigned addrlen; +}; + +#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 + +/*-------------------------------------------------------------------------*/ + +#define io_limit PAGE_SIZE /* bytes */ + +static ssize_t +at25_ee_read( + struct at25_data *at25, + char *buf, + unsigned offset, + size_t count +) +{ + u8 command[EE_MAXADDRLEN + 1]; + u8 *cp; + ssize_t status; + struct spi_transfer t[2]; + struct spi_message m; + + 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); + + mutex_lock(&at25->lock); + + /* 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->spi->dev, + "read %Zd bytes at %d --> %d\n", + count, offset, (int) status); + + mutex_unlock(&at25->lock); + return status ? status : count; +} + +static ssize_t +at25_bin_read(struct kobject *kobj, char *buf, loff_t off, size_t count) +{ + struct device *dev; + struct at25_data *at25; + + dev = container_of(kobj, struct device, kobj); + at25 = dev_get_drvdata(dev); + + if (unlikely(off >= at25->bin.size)) + return 0; + if ((off + count) > at25->bin.size) + count = at25->bin.size - off; + if (unlikely(!count)) + return count; + + return at25_ee_read(at25, buf, off, count); +} + + +static ssize_t +at25_ee_write(struct at25_data *at25, char *buf, loff_t off, size_t count) +{ + ssize_t status = 0; + unsigned written = 0; + unsigned buf_size; + u8 *bounce; + + /* Temp buffer starts with command and address */ + buf_size = at25->chip.page_size; + if (buf_size > io_limit) + buf_size = io_limit; + bounce = kmalloc(buf_size + at25->addrlen + 1, GFP_KERNEL); + if (!bounce) + return -ENOMEM; + + /* 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; + mutex_lock(&at25->lock); + do { + unsigned long timeout, retries; + unsigned segment; + unsigned offset = (unsigned) off; + u8 *cp = bounce + 1; + + *cp = AT25_WREN; + status = spi_write(at25->spi, cp, 1); + if (status < 0) { + dev_dbg(&at25->spi->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->spi->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 */ + timeout = jiffies + msecs_to_jiffies(EE_TIMEOUT); + retries = 0; + do { + int sr; + + sr = spi_w8r8(at25->spi, AT25_RDSR); + if (sr < 0 || (sr & AT25_SR_nRDY)) { + dev_dbg(&at25->spi->dev, + "rdsr --> %d (%02x)\n", sr, sr); + /* at HZ=100, this is sloooow */ + msleep(1); + continue; + } + if (!(sr & AT25_SR_nRDY)) + break; + } while (retries++ < 3 || time_before_eq(jiffies, timeout)); + + if (time_after(jiffies, timeout)) { + dev_err(&at25->spi->dev, + "write %d bytes offset %d, " + "timeout after %u msecs\n", + segment, offset, + jiffies_to_msecs(jiffies - + (timeout - EE_TIMEOUT))); + status = -ETIMEDOUT; + break; + } + + off += segment; + buf += segment; + count -= segment; + written += segment; + + } while (count > 0); + + mutex_unlock(&at25->lock); + + kfree(bounce); + return written ? written : status; +} + +static ssize_t +at25_bin_write(struct kobject *kobj, char *buf, loff_t off, size_t count) +{ + struct device *dev; + struct at25_data *at25; + + dev = container_of(kobj, struct device, kobj); + at25 = dev_get_drvdata(dev); + + if (unlikely(off >= at25->bin.size)) + return -EFBIG; + if ((off + count) > at25->bin.size) + count = at25->bin.size - off; + if (unlikely(!count)) + return count; + + return at25_ee_write(at25, buf, off, count); +} + +/*-------------------------------------------------------------------------*/ + +static int at25_probe(struct spi_device *spi) +{ + struct at25_data *at25 = NULL; + const struct spi_eeprom *chip; + int err; + int sr; + int addrlen; + + /* Chip description */ + chip = spi->dev.platform_data; + if (!chip) { + dev_dbg(&spi->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(&spi->dev, "unsupported address type\n"); + err = -EINVAL; + goto fail; + } + + /* 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(spi, AT25_RDSR); + if (sr < 0 || sr & AT25_SR_nRDY) { + dev_dbg(&at25->spi->dev, "rdsr --> %d (%02x)\n", sr, sr); + err = -ENXIO; + goto fail; + } + + if (!(at25 = kzalloc(sizeof *at25, GFP_KERNEL))) { + err = -ENOMEM; + goto fail; + } + + mutex_init(&at25->lock); + at25->chip = *chip; + at25->spi = spi_dev_get(spi); + dev_set_drvdata(&spi->dev, at25); + at25->addrlen = addrlen; + + /* Export the EEPROM bytes through sysfs, since that's convenient. + * Default to root-only access to the data; EEPROMs often hold data + * that's sensitive for read and/or write, like ethernet addresses, + * security codes, board-specific manufacturing calibrations, etc. + */ + at25->bin.attr.name = "eeprom"; + at25->bin.attr.mode = S_IRUSR; + at25->bin.attr.owner = THIS_MODULE; + at25->bin.read = at25_bin_read; + + at25->bin.size = at25->chip.byte_len; + if (!(chip->flags & EE_READONLY)) { + at25->bin.write = at25_bin_write; + at25->bin.attr.mode |= S_IWUSR; + } + + err = sysfs_create_bin_file(&spi->dev.kobj, &at25->bin); + if (err) + goto fail; + + dev_info(&spi->dev, "%Zd %s %s eeprom%s, pagesize %u\n", + (at25->bin.size < 1024) + ? at25->bin.size + : (at25->bin.size / 1024), + (at25->bin.size < 1024) ? "Byte" : "KByte", + at25->chip.name, + (chip->flags & EE_READONLY) ? " (readonly)" : "", + at25->chip.page_size); + return 0; +fail: + dev_dbg(&spi->dev, "probe err %d\n", err); + kfree(at25); + return err; +} + +static int __devexit at25_remove(struct spi_device *spi) +{ + struct at25_data *at25; + + at25 = dev_get_drvdata(&spi->dev); + sysfs_remove_bin_file(&spi->dev.kobj, &at25->bin); + kfree(at25); + return 0; +} + +/*-------------------------------------------------------------------------*/ + +static struct spi_driver at25_driver = { + .driver = { + .name = "at25", + .owner = THIS_MODULE, + }, + .probe = at25_probe, + .remove = __devexit_p(at25_remove), +}; + +static int __init at25_init(void) +{ + return spi_register_driver(&at25_driver); +} +module_init(at25_init); + +static void __exit at25_exit(void) +{ + spi_unregister_driver(&at25_driver); +} +module_exit(at25_exit); + +MODULE_DESCRIPTION("Driver for most SPI EEPROMs"); +MODULE_AUTHOR("David Brownell"); +MODULE_LICENSE("GPL"); + diff --git a/include/linux/spi/eeprom.h b/include/linux/spi/eeprom.h new file mode 100644 index 00000000000..1085212c446 --- /dev/null +++ b/include/linux/spi/eeprom.h @@ -0,0 +1,22 @@ +#ifndef __LINUX_SPI_EEPROM_H +#define __LINUX_SPI_EEPROM_H + +/* + * Put one of these structures in platform_data for SPI EEPROMS handled + * by the "at25" driver. On SPI, most EEPROMS understand the same core + * command set. If you need to support EEPROMs that don't yet fit, add + * flags to support those protocol options. These values all come from + * the chip datasheets. + */ +struct spi_eeprom { + u32 byte_len; + char name[10]; + u16 page_size; /* for writes */ + u16 flags; +#define EE_ADDR1 0x0001 /* 8 bit addrs */ +#define EE_ADDR2 0x0002 /* 16 bit addrs */ +#define EE_ADDR3 0x0004 /* 24 bit addrs */ +#define EE_READONLY 0x0008 /* disallow writes */ +}; + +#endif /* __LINUX_SPI_EEPROM_H */ |