|  | /* | 
|  | * 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 file *filp, 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 file *filp, 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"); |