| /* |
| * 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> |
| |
| |
| /* |
| * 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 spi_device *spi; |
| struct memory_accessor mem; |
| 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; |
| |
| if (unlikely(offset >= at25->bin.size)) |
| return 0; |
| if ((offset + count) > at25->bin.size) |
| count = at25->bin.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); |
| |
| 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, struct bin_attribute *bin_attr, |
| 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); |
| |
| return at25_ee_read(at25, buf, off, count); |
| } |
| |
| |
| static ssize_t |
| at25_ee_write(struct at25_data *at25, const char *buf, loff_t off, |
| size_t count) |
| { |
| ssize_t status = 0; |
| unsigned written = 0; |
| unsigned buf_size; |
| u8 *bounce; |
| |
| if (unlikely(off >= at25->bin.size)) |
| return -EFBIG; |
| if ((off + count) > at25->bin.size) |
| count = at25->bin.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 = 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; |
| int sr; |
| |
| *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 { |
| |
| 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 ((sr < 0) || (sr & AT25_SR_nRDY)) { |
| 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, struct bin_attribute *bin_attr, |
| 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); |
| |
| return at25_ee_write(at25, buf, off, count); |
| } |
| |
| /*-------------------------------------------------------------------------*/ |
| |
| /* Let in-kernel code access the eeprom data. */ |
| |
| static ssize_t at25_mem_read(struct memory_accessor *mem, char *buf, |
| off_t offset, size_t count) |
| { |
| struct at25_data *at25 = container_of(mem, struct at25_data, mem); |
| |
| return at25_ee_read(at25, buf, offset, count); |
| } |
| |
| static ssize_t at25_mem_write(struct memory_accessor *mem, const char *buf, |
| off_t offset, size_t count) |
| { |
| struct at25_data *at25 = container_of(mem, struct at25_data, mem); |
| |
| return at25_ee_write(at25, buf, offset, 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(&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. |
| * And maybe to other kernel code; it might hold a board's Ethernet |
| * address, or board-specific calibration data generated on the |
| * manufacturing floor. |
| * |
| * 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. |
| */ |
| sysfs_bin_attr_init(&at25->bin); |
| at25->bin.attr.name = "eeprom"; |
| at25->bin.attr.mode = S_IRUSR; |
| at25->bin.read = at25_bin_read; |
| at25->mem.read = at25_mem_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; |
| at25->mem.write = at25_mem_write; |
| } |
| |
| err = sysfs_create_bin_file(&spi->dev.kobj, &at25->bin); |
| if (err) |
| goto fail; |
| |
| if (chip->setup) |
| chip->setup(&at25->mem, chip->context); |
| |
| 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"); |
| MODULE_ALIAS("spi:at25"); |