* Re: [PATCH 2/2] Add at24 based EEPROMs to the eeprom_dev hardware class
@ 2014-01-23 7:44 Laszlo Papp
2014-01-23 15:05 ` Curt Brune
2014-01-23 17:25 ` Wolfram Sang
0 siblings, 2 replies; 8+ messages in thread
From: Laszlo Papp @ 2014-01-23 7:44 UTC (permalink / raw)
To: Curt Brune
Cc: Thomas De Schampheleire, gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r,
Shrijeet Mukherjee, wolfram-z923LK4zBo2bacvFa/9K2g,
linux-i2c-u79uwXL29TY76Z2rM5mHXA, LKML
On Wed, Jan 22, 2014 at 5:23 PM, Curt Brune <curt-qUQiAmfTcIp+XZJcv9eMoEEOCMrvLtNR@public.gmane.org> wrote:
> During device instantiation have the at24 driver add the new device to
> the eeprom_dev hardware class. The functionality is enabled by
> CONFIG_EEPROM_CLASS.
>
> Signed-off-by: Curt Brune <curt-qUQiAmfTcIp+XZJcv9eMoEEOCMrvLtNR@public.gmane.org>
> ---
> drivers/misc/eeprom/at24.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> index d87f77f..07782ea 100644
> --- a/drivers/misc/eeprom/at24.c
> +++ b/drivers/misc/eeprom/at24.c
> @@ -1,170 +1,177 @@
> /*
> * at24.c - handle most I2C EEPROMs
> *
> * Copyright (C) 2005-2007 David Brownell
> * Copyright (C) 2008 Wolfram Sang, Pengutronix
> *
> * 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/mutex.h>
> #include <linux/sysfs.h>
> #include <linux/mod_devicetable.h>
> #include <linux/log2.h>
> #include <linux/bitops.h>
> #include <linux/jiffies.h>
> #include <linux/of.h>
> #include <linux/i2c.h>
> #include <linux/platform_data/at24.h>
>
> +#ifdef CONFIG_EEPROM_CLASS
> +#include <linux/eeprom_class.h>
> +#endif
> +
> /*
> * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
> * Differences between different vendor product lines (like Atmel AT24C or
> * MicroChip 24LC, etc) won't much matter for typical read/write access.
> * There are also I2C RAM chips, likewise interchangeable. One example
> * would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
> *
> * However, misconfiguration can lose data. "Set 16-bit memory address"
> * to a part with 8-bit addressing will overwrite data. Writing with too
> * big a page size also loses data. And it's not safe to assume that the
> * conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
> * uses 0x51, for just one example.
> *
> * Accordingly, explicit board-specific configuration data should be used
> * in almost all cases. (One partial exception is an SMBus used to access
> * "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
> *
> * So this driver uses "new style" I2C driver binding, expecting to be
> * told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
> * similar kernel-resident tables; or, configuration data coming from
> * a bootloader.
> *
> * Other than binding model, current differences from "eeprom" driver are
> * that this one handles write access and isn't restricted to 24c02 devices.
> * It also handles larger devices (32 kbit and up) with two-byte addresses,
> * which won't work on pure SMBus systems.
> */
>
> struct at24_data {
> struct at24_platform_data chip;
> struct memory_accessor macc;
> int use_smbus;
>
> /*
> * Lock protects against activities from other Linux tasks,
> * but not from changes by other I2C masters.
> */
> struct mutex lock;
> struct bin_attribute bin;
>
> u8 *writebuf;
> unsigned write_max;
> unsigned num_addresses;
>
> +#ifdef CONFIG_EEPROM_CLASS
> + struct device *eeprom_dev;
> +#endif
> /*
> * Some chips tie up multiple I2C addresses; dummy devices reserve
> * them for us, and we'll use them with SMBus calls.
> */
> struct i2c_client *client[];
> };
>
> /*
> * This parameter is to help this driver avoid blocking other drivers out
> * of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
> * clock, one 256 byte read takes about 1/43 second which is excessive;
> * but the 1/170 second it takes at 400 kHz may be quite reasonable; and
> * at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
> *
> * This value is forced to be a power of two so that writes align on pages.
> */
> static unsigned io_limit = 128;
> module_param(io_limit, uint, 0);
> MODULE_PARM_DESC(io_limit, "Maximum bytes per I/O (default 128)");
>
> /*
> * Specs often allow 5 msec for a page write, sometimes 20 msec;
> * it's important to recover from write timeouts.
> */
> static unsigned write_timeout = 25;
> module_param(write_timeout, uint, 0);
> MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
>
> #define AT24_SIZE_BYTELEN 5
> #define AT24_SIZE_FLAGS 8
>
> #define AT24_BITMASK(x) (BIT(x) - 1)
>
> /* create non-zero magic value for given eeprom parameters */
> #define AT24_DEVICE_MAGIC(_len, _flags) \
> ((1 << AT24_SIZE_FLAGS | (_flags)) \
> << AT24_SIZE_BYTELEN | ilog2(_len))
>
> static const struct i2c_device_id at24_ids[] = {
> /* needs 8 addresses as A0-A2 are ignored */
> { "24c00", AT24_DEVICE_MAGIC(128 / 8, AT24_FLAG_TAKE8ADDR) },
> /* old variants can't be handled with this generic entry! */
> { "24c01", AT24_DEVICE_MAGIC(1024 / 8, 0) },
> { "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) },
> /* spd is a 24c02 in memory DIMMs */
> { "spd", AT24_DEVICE_MAGIC(2048 / 8,
> AT24_FLAG_READONLY | AT24_FLAG_IRUGO) },
> { "24c04", AT24_DEVICE_MAGIC(4096 / 8, 0) },
> /* 24rf08 quirk is handled at i2c-core */
> { "24c08", AT24_DEVICE_MAGIC(8192 / 8, 0) },
> { "24c16", AT24_DEVICE_MAGIC(16384 / 8, 0) },
> { "24c32", AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16) },
> { "24c64", AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16) },
> { "24c128", AT24_DEVICE_MAGIC(131072 / 8, AT24_FLAG_ADDR16) },
> { "24c256", AT24_DEVICE_MAGIC(262144 / 8, AT24_FLAG_ADDR16) },
> { "24c512", AT24_DEVICE_MAGIC(524288 / 8, AT24_FLAG_ADDR16) },
> { "24c1024", AT24_DEVICE_MAGIC(1048576 / 8, AT24_FLAG_ADDR16) },
> { "at24", 0 },
> { /* END OF LIST */ }
> };
> MODULE_DEVICE_TABLE(i2c, at24_ids);
>
> /*-------------------------------------------------------------------------*/
>
> /*
> * This routine supports chips which consume multiple I2C addresses. It
> * computes the addressing information to be used for a given r/w request.
> * Assumes that sanity checks for offset happened at sysfs-layer.
> */
> static struct i2c_client *at24_translate_offset(struct at24_data *at24,
> unsigned *offset)
> {
> unsigned i;
>
> if (at24->chip.flags & AT24_FLAG_ADDR16) {
> i = *offset >> 16;
> *offset &= 0xffff;
> } else {
> i = *offset >> 8;
> *offset &= 0xff;
> }
>
> return at24->client[i];
> }
>
> static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,
> unsigned offset, size_t count)
> {
> struct i2c_msg msg[2];
> u8 msgbuf[2];
> struct i2c_client *client;
> unsigned long timeout, read_time;
> int status, i;
>
> memset(msg, 0, sizeof(msg));
>
> /*
> * REVISIT some multi-address chips don't rollover page reads to
> * the next slave address, so we may need to truncate the count.
> * Those chips might need another quirk flag.
> @@ -524,173 +531,186 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
> return -EINVAL;
> }
> if (!is_power_of_2(chip.page_size))
> dev_warn(&client->dev,
> "page_size looks suspicious (no power of 2)!\n");
>
> /* Use I2C operations unless we're stuck with SMBus extensions. */
> if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
> if (chip.flags & AT24_FLAG_ADDR16)
> return -EPFNOSUPPORT;
>
> if (i2c_check_functionality(client->adapter,
> I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
> use_smbus = I2C_SMBUS_I2C_BLOCK_DATA;
> } else if (i2c_check_functionality(client->adapter,
> I2C_FUNC_SMBUS_READ_WORD_DATA)) {
> use_smbus = I2C_SMBUS_WORD_DATA;
> } else if (i2c_check_functionality(client->adapter,
> I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
> use_smbus = I2C_SMBUS_BYTE_DATA;
> } else {
> return -EPFNOSUPPORT;
> }
> }
>
> if (chip.flags & AT24_FLAG_TAKE8ADDR)
> num_addresses = 8;
> else
> num_addresses = DIV_ROUND_UP(chip.byte_len,
> (chip.flags & AT24_FLAG_ADDR16) ? 65536 : 256);
>
> at24 = devm_kzalloc(&client->dev, sizeof(struct at24_data) +
> num_addresses * sizeof(struct i2c_client *), GFP_KERNEL);
> if (!at24)
> return -ENOMEM;
>
> mutex_init(&at24->lock);
> at24->use_smbus = use_smbus;
> at24->chip = chip;
> at24->num_addresses = num_addresses;
>
> /*
> * Export the EEPROM bytes through sysfs, since that's convenient.
> * By default, only root should see the data (maybe passwords etc)
> */
> sysfs_bin_attr_init(&at24->bin);
> at24->bin.attr.name = "eeprom";
> at24->bin.attr.mode = chip.flags & AT24_FLAG_IRUGO ? S_IRUGO : S_IRUSR;
> at24->bin.read = at24_bin_read;
> at24->bin.size = chip.byte_len;
>
> at24->macc.read = at24_macc_read;
>
> writable = !(chip.flags & AT24_FLAG_READONLY);
> if (writable) {
> if (!use_smbus || i2c_check_functionality(client->adapter,
> I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
>
> unsigned write_max = chip.page_size;
>
> at24->macc.write = at24_macc_write;
>
> at24->bin.write = at24_bin_write;
> at24->bin.attr.mode |= S_IWUSR;
>
> if (write_max > io_limit)
> write_max = io_limit;
> if (use_smbus && write_max > I2C_SMBUS_BLOCK_MAX)
> write_max = I2C_SMBUS_BLOCK_MAX;
> at24->write_max = write_max;
>
> /* buffer (data + address at the beginning) */
> at24->writebuf = devm_kzalloc(&client->dev,
> write_max + 2, GFP_KERNEL);
> if (!at24->writebuf)
> return -ENOMEM;
> } else {
> dev_warn(&client->dev,
> "cannot write due to controller restrictions.");
> }
> }
>
> at24->client[0] = client;
>
> /* use dummy devices for multiple-address chips */
> for (i = 1; i < num_addresses; i++) {
> at24->client[i] = i2c_new_dummy(client->adapter,
> client->addr + i);
> if (!at24->client[i]) {
> dev_err(&client->dev, "address 0x%02x unavailable\n",
> client->addr + i);
> err = -EADDRINUSE;
> goto err_clients;
> }
> }
>
> err = sysfs_create_bin_file(&client->dev.kobj, &at24->bin);
> if (err)
> goto err_clients;
>
> +#ifdef CONFIG_EEPROM_CLASS
> + at24->eeprom_dev = eeprom_device_register(&client->dev);
> + if (IS_ERR(at24->eeprom_dev)) {
> + dev_err(&client->dev, "error registering eeprom device.\n");
> + err = PTR_ERR(at24->eeprom_dev);
> + goto err_clients;
> + }
> +#endif
> +
> i2c_set_clientdata(client, at24);
>
> dev_info(&client->dev, "%zu byte %s EEPROM, %s, %u bytes/write\n",
> at24->bin.size, client->name,
> writable ? "writable" : "read-only", at24->write_max);
> if (use_smbus == I2C_SMBUS_WORD_DATA ||
> use_smbus == I2C_SMBUS_BYTE_DATA) {
> dev_notice(&client->dev, "Falling back to %s reads, "
> "performance will suffer\n", use_smbus ==
> I2C_SMBUS_WORD_DATA ? "word" : "byte");
> }
>
> /* export data to kernel code */
> if (chip.setup)
> chip.setup(&at24->macc, chip.context);
>
> return 0;
>
> err_clients:
> for (i = 1; i < num_addresses; i++)
> if (at24->client[i])
> i2c_unregister_device(at24->client[i]);
>
> return err;
> }
>
> static int at24_remove(struct i2c_client *client)
> {
> struct at24_data *at24;
> int i;
>
> at24 = i2c_get_clientdata(client);
> sysfs_remove_bin_file(&client->dev.kobj, &at24->bin);
>
> for (i = 1; i < at24->num_addresses; i++)
> i2c_unregister_device(at24->client[i]);
>
> +#ifdef CONFIG_EEPROM_CLASS
> + eeprom_device_unregister(at24->eeprom_dev);
> +#endif
> +
> return 0;
> }
>
> /*-------------------------------------------------------------------------*/
>
> static struct i2c_driver at24_driver = {
> .driver = {
> .name = "at24",
> .owner = THIS_MODULE,
> },
> .probe = at24_probe,
> .remove = at24_remove,
> .id_table = at24_ids,
> };
>
> static int __init at24_init(void)
> {
> if (!io_limit) {
> pr_err("at24: io_limit must not be 0!\n");
> return -EINVAL;
> }
>
> io_limit = rounddown_pow_of_two(io_limit);
> return i2c_add_driver(&at24_driver);
> }
> module_init(at24_init);
>
> static void __exit at24_exit(void)
> {
> i2c_del_driver(&at24_driver);
> }
> module_exit(at24_exit);
Couldn't you use module_i2c_driver() instead of this?
> MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
> MODULE_AUTHOR("David Brownell and Wolfram Sang");
I would personally put your name in here if I were you, otherwise
David and Wolfram might get contacted by some people instead of you
(at least based on this).
PS.: Fixing the broken i2c mailing list typo, and updating Wolfram's
address from the broken (obsolete?) version.
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH 2/2] Add at24 based EEPROMs to the eeprom_dev hardware class
2014-01-23 7:44 [PATCH 2/2] Add at24 based EEPROMs to the eeprom_dev hardware class Laszlo Papp
@ 2014-01-23 15:05 ` Curt Brune
[not found] ` <20140123150524.GH29955-qUQiAmfTcIp+XZJcv9eMoEEOCMrvLtNR@public.gmane.org>
2014-01-23 17:25 ` Wolfram Sang
1 sibling, 1 reply; 8+ messages in thread
From: Curt Brune @ 2014-01-23 15:05 UTC (permalink / raw)
To: Laszlo Papp
Cc: Thomas De Schampheleire, gregkh, Shrijeet Mukherjee, wolfram,
linux-i2c, LKML
On Thu Jan 23 07:44, Laszlo Papp wrote:
> On Wed, Jan 22, 2014 at 5:23 PM, Curt Brune <curt@cumulusnetworks.com> wrote:
> > During device instantiation have the at24 driver add the new device to
> > the eeprom_dev hardware class. The functionality is enabled by
> > CONFIG_EEPROM_CLASS.
[snip]
> > static void __exit at24_exit(void)
> > {
> > i2c_del_driver(&at24_driver);
> > }
> > module_exit(at24_exit);
>
> Couldn't you use module_i2c_driver() instead of this?
I'm not sure what you mean.
Do you mean should the class registration/unregistration be put in
module_i2c_driver()? That would not work as not all i2c devices are
eeproms.
>
> > MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
> > MODULE_AUTHOR("David Brownell and Wolfram Sang");
>
> I would personally put your name in here if I were you, otherwise
> David and Wolfram might get contacted by some people instead of you
> (at least based on this).
Hmmm. I don't know. I didn't change the driver very much, just
added about 10 lines to a perfectly fine driver. git-blame would
point right at me for anything to do with this patch.
>
> PS.: Fixing the broken i2c mailing list typo, and updating Wolfram's
> address from the broken (obsolete?) version.
Thanks for fixing that.
Cheers,
Curt
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH 2/2] Add at24 based EEPROMs to the eeprom_dev hardware class
2014-01-23 7:44 [PATCH 2/2] Add at24 based EEPROMs to the eeprom_dev hardware class Laszlo Papp
2014-01-23 15:05 ` Curt Brune
@ 2014-01-23 17:25 ` Wolfram Sang
2014-01-23 17:51 ` Laszlo Papp
1 sibling, 1 reply; 8+ messages in thread
From: Wolfram Sang @ 2014-01-23 17:25 UTC (permalink / raw)
To: Laszlo Papp
Cc: Curt Brune, Thomas De Schampheleire, gregkh, Shrijeet Mukherjee,
wolfram, linux-i2c, LKML
[-- Attachment #1: Type: text/plain, Size: 1046 bytes --]
Hi,
No need to quote the whole message if you reply only to a bit of it.
> > module_init(at24_init);
> >
> > static void __exit at24_exit(void)
> > {
> > i2c_del_driver(&at24_driver);
> > }
> > module_exit(at24_exit);
>
> Couldn't you use module_i2c_driver() instead of this?
He didn't write that code. It doesn't have a + at the beginning. He used
the whole driver as context, which is highly unusual. A context of 3
lines is usually good enough.
>
> > MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
> > MODULE_AUTHOR("David Brownell and Wolfram Sang");
>
> I would personally put your name in here if I were you, otherwise
> David and Wolfram might get contacted by some people instead of you
> (at least based on this).
See above. He changed only 10 lines. Not enough for copyright IMO.
> PS.: Fixing the broken i2c mailing list typo, and updating Wolfram's
> address from the broken (obsolete?) version.
It came through to the i2c list? What was wrong?
Regards,
Wolfram
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^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH 2/2] Add at24 based EEPROMs to the eeprom_dev hardware class
2014-01-23 17:25 ` Wolfram Sang
@ 2014-01-23 17:51 ` Laszlo Papp
[not found] ` <CAOMwXhPqnSNWtPMo7Qrr-O3qAqtjju7au7Mudckp7kN50yQW3A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
0 siblings, 1 reply; 8+ messages in thread
From: Laszlo Papp @ 2014-01-23 17:51 UTC (permalink / raw)
To: Wolfram Sang
Cc: Curt Brune, Thomas De Schampheleire, gregkh, Shrijeet Mukherjee,
wolfram, linux-i2c, LKML
On Thu, Jan 23, 2014 at 5:25 PM, Wolfram Sang <wsa@the-dreams.de> wrote:
> Hi,
>
> No need to quote the whole message if you reply only to a bit of it.
>
>> > module_init(at24_init);
>> >
>> > static void __exit at24_exit(void)
>> > {
>> > i2c_del_driver(&at24_driver);
>> > }
>> > module_exit(at24_exit);
>>
>> Couldn't you use module_i2c_driver() instead of this?
>
> He didn't write that code. It doesn't have a + at the beginning. He used
> the whole driver as context, which is highly unusual. A context of 3
> lines is usually good enough.
Right. I will send a patch addressing that separately.
>> > MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
>> > MODULE_AUTHOR("David Brownell and Wolfram Sang");
>>
>> I would personally put your name in here if I were you, otherwise
>> David and Wolfram might get contacted by some people instead of you
>> (at least based on this).
>
> See above. He changed only 10 lines. Not enough for copyright IMO.
Well, it is not the Copyrights section, or you are saying the same
people should go to MODULE_AUTHOR as in the Copyrights section, even
if it is potentially several names? I thought this would be the name
of the person who put the file together even if from existing sources.
>> PS.: Fixing the broken i2c mailing list typo, and updating Wolfram's
>> address from the broken (obsolete?) version.
>
> It came through to the i2c list? What was wrong?
Yes, it did, _after_ fixing the typo in the mailing list address.
Check the original mailing list address typed for details.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH 2/2] Add at24 based EEPROMs to the eeprom_dev hardware class
@ 2014-01-22 17:47 Curt Brune
0 siblings, 0 replies; 8+ messages in thread
From: Curt Brune @ 2014-01-22 17:47 UTC (permalink / raw)
To: Wolfram Sang
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA,
curt-qUQiAmfTcIp+XZJcv9eMoEEOCMrvLtNR
During device instantiation have the at24 driver add the new device to
the eeprom_dev hardware class. The functionality is enabled by
CONFIG_EEPROM_CLASS.
Signed-off-by: Curt Brune <curt-qUQiAmfTcIp+XZJcv9eMoEEOCMrvLtNR@public.gmane.org>
---
drivers/misc/eeprom/at24.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index d87f77f..07782ea 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -1,170 +1,177 @@
/*
* at24.c - handle most I2C EEPROMs
*
* Copyright (C) 2005-2007 David Brownell
* Copyright (C) 2008 Wolfram Sang, Pengutronix
*
* 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/mutex.h>
#include <linux/sysfs.h>
#include <linux/mod_devicetable.h>
#include <linux/log2.h>
#include <linux/bitops.h>
#include <linux/jiffies.h>
#include <linux/of.h>
#include <linux/i2c.h>
#include <linux/platform_data/at24.h>
+#ifdef CONFIG_EEPROM_CLASS
+#include <linux/eeprom_class.h>
+#endif
+
/*
* I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
* Differences between different vendor product lines (like Atmel AT24C or
* MicroChip 24LC, etc) won't much matter for typical read/write access.
* There are also I2C RAM chips, likewise interchangeable. One example
* would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
*
* However, misconfiguration can lose data. "Set 16-bit memory address"
* to a part with 8-bit addressing will overwrite data. Writing with too
* big a page size also loses data. And it's not safe to assume that the
* conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
* uses 0x51, for just one example.
*
* Accordingly, explicit board-specific configuration data should be used
* in almost all cases. (One partial exception is an SMBus used to access
* "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
*
* So this driver uses "new style" I2C driver binding, expecting to be
* told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
* similar kernel-resident tables; or, configuration data coming from
* a bootloader.
*
* Other than binding model, current differences from "eeprom" driver are
* that this one handles write access and isn't restricted to 24c02 devices.
* It also handles larger devices (32 kbit and up) with two-byte addresses,
* which won't work on pure SMBus systems.
*/
struct at24_data {
struct at24_platform_data chip;
struct memory_accessor macc;
int use_smbus;
/*
* Lock protects against activities from other Linux tasks,
* but not from changes by other I2C masters.
*/
struct mutex lock;
struct bin_attribute bin;
u8 *writebuf;
unsigned write_max;
unsigned num_addresses;
+#ifdef CONFIG_EEPROM_CLASS
+ struct device *eeprom_dev;
+#endif
/*
* Some chips tie up multiple I2C addresses; dummy devices reserve
* them for us, and we'll use them with SMBus calls.
*/
struct i2c_client *client[];
};
/*
* This parameter is to help this driver avoid blocking other drivers out
* of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
* clock, one 256 byte read takes about 1/43 second which is excessive;
* but the 1/170 second it takes at 400 kHz may be quite reasonable; and
* at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
*
* This value is forced to be a power of two so that writes align on pages.
*/
static unsigned io_limit = 128;
module_param(io_limit, uint, 0);
MODULE_PARM_DESC(io_limit, "Maximum bytes per I/O (default 128)");
/*
* Specs often allow 5 msec for a page write, sometimes 20 msec;
* it's important to recover from write timeouts.
*/
static unsigned write_timeout = 25;
module_param(write_timeout, uint, 0);
MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
#define AT24_SIZE_BYTELEN 5
#define AT24_SIZE_FLAGS 8
#define AT24_BITMASK(x) (BIT(x) - 1)
/* create non-zero magic value for given eeprom parameters */
#define AT24_DEVICE_MAGIC(_len, _flags) \
((1 << AT24_SIZE_FLAGS | (_flags)) \
<< AT24_SIZE_BYTELEN | ilog2(_len))
static const struct i2c_device_id at24_ids[] = {
/* needs 8 addresses as A0-A2 are ignored */
{ "24c00", AT24_DEVICE_MAGIC(128 / 8, AT24_FLAG_TAKE8ADDR) },
/* old variants can't be handled with this generic entry! */
{ "24c01", AT24_DEVICE_MAGIC(1024 / 8, 0) },
{ "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) },
/* spd is a 24c02 in memory DIMMs */
{ "spd", AT24_DEVICE_MAGIC(2048 / 8,
AT24_FLAG_READONLY | AT24_FLAG_IRUGO) },
{ "24c04", AT24_DEVICE_MAGIC(4096 / 8, 0) },
/* 24rf08 quirk is handled at i2c-core */
{ "24c08", AT24_DEVICE_MAGIC(8192 / 8, 0) },
{ "24c16", AT24_DEVICE_MAGIC(16384 / 8, 0) },
{ "24c32", AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16) },
{ "24c64", AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16) },
{ "24c128", AT24_DEVICE_MAGIC(131072 / 8, AT24_FLAG_ADDR16) },
{ "24c256", AT24_DEVICE_MAGIC(262144 / 8, AT24_FLAG_ADDR16) },
{ "24c512", AT24_DEVICE_MAGIC(524288 / 8, AT24_FLAG_ADDR16) },
{ "24c1024", AT24_DEVICE_MAGIC(1048576 / 8, AT24_FLAG_ADDR16) },
{ "at24", 0 },
{ /* END OF LIST */ }
};
MODULE_DEVICE_TABLE(i2c, at24_ids);
/*-------------------------------------------------------------------------*/
/*
* This routine supports chips which consume multiple I2C addresses. It
* computes the addressing information to be used for a given r/w request.
* Assumes that sanity checks for offset happened at sysfs-layer.
*/
static struct i2c_client *at24_translate_offset(struct at24_data *at24,
unsigned *offset)
{
unsigned i;
if (at24->chip.flags & AT24_FLAG_ADDR16) {
i = *offset >> 16;
*offset &= 0xffff;
} else {
i = *offset >> 8;
*offset &= 0xff;
}
return at24->client[i];
}
static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,
unsigned offset, size_t count)
{
struct i2c_msg msg[2];
u8 msgbuf[2];
struct i2c_client *client;
unsigned long timeout, read_time;
int status, i;
memset(msg, 0, sizeof(msg));
/*
* REVISIT some multi-address chips don't rollover page reads to
* the next slave address, so we may need to truncate the count.
* Those chips might need another quirk flag.
@@ -524,173 +531,186 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
return -EINVAL;
}
if (!is_power_of_2(chip.page_size))
dev_warn(&client->dev,
"page_size looks suspicious (no power of 2)!\n");
/* Use I2C operations unless we're stuck with SMBus extensions. */
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
if (chip.flags & AT24_FLAG_ADDR16)
return -EPFNOSUPPORT;
if (i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
use_smbus = I2C_SMBUS_I2C_BLOCK_DATA;
} else if (i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_READ_WORD_DATA)) {
use_smbus = I2C_SMBUS_WORD_DATA;
} else if (i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
use_smbus = I2C_SMBUS_BYTE_DATA;
} else {
return -EPFNOSUPPORT;
}
}
if (chip.flags & AT24_FLAG_TAKE8ADDR)
num_addresses = 8;
else
num_addresses = DIV_ROUND_UP(chip.byte_len,
(chip.flags & AT24_FLAG_ADDR16) ? 65536 : 256);
at24 = devm_kzalloc(&client->dev, sizeof(struct at24_data) +
num_addresses * sizeof(struct i2c_client *), GFP_KERNEL);
if (!at24)
return -ENOMEM;
mutex_init(&at24->lock);
at24->use_smbus = use_smbus;
at24->chip = chip;
at24->num_addresses = num_addresses;
/*
* Export the EEPROM bytes through sysfs, since that's convenient.
* By default, only root should see the data (maybe passwords etc)
*/
sysfs_bin_attr_init(&at24->bin);
at24->bin.attr.name = "eeprom";
at24->bin.attr.mode = chip.flags & AT24_FLAG_IRUGO ? S_IRUGO : S_IRUSR;
at24->bin.read = at24_bin_read;
at24->bin.size = chip.byte_len;
at24->macc.read = at24_macc_read;
writable = !(chip.flags & AT24_FLAG_READONLY);
if (writable) {
if (!use_smbus || i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
unsigned write_max = chip.page_size;
at24->macc.write = at24_macc_write;
at24->bin.write = at24_bin_write;
at24->bin.attr.mode |= S_IWUSR;
if (write_max > io_limit)
write_max = io_limit;
if (use_smbus && write_max > I2C_SMBUS_BLOCK_MAX)
write_max = I2C_SMBUS_BLOCK_MAX;
at24->write_max = write_max;
/* buffer (data + address at the beginning) */
at24->writebuf = devm_kzalloc(&client->dev,
write_max + 2, GFP_KERNEL);
if (!at24->writebuf)
return -ENOMEM;
} else {
dev_warn(&client->dev,
"cannot write due to controller restrictions.");
}
}
at24->client[0] = client;
/* use dummy devices for multiple-address chips */
for (i = 1; i < num_addresses; i++) {
at24->client[i] = i2c_new_dummy(client->adapter,
client->addr + i);
if (!at24->client[i]) {
dev_err(&client->dev, "address 0x%02x unavailable\n",
client->addr + i);
err = -EADDRINUSE;
goto err_clients;
}
}
err = sysfs_create_bin_file(&client->dev.kobj, &at24->bin);
if (err)
goto err_clients;
+#ifdef CONFIG_EEPROM_CLASS
+ at24->eeprom_dev = eeprom_device_register(&client->dev);
+ if (IS_ERR(at24->eeprom_dev)) {
+ dev_err(&client->dev, "error registering eeprom device.\n");
+ err = PTR_ERR(at24->eeprom_dev);
+ goto err_clients;
+ }
+#endif
+
i2c_set_clientdata(client, at24);
dev_info(&client->dev, "%zu byte %s EEPROM, %s, %u bytes/write\n",
at24->bin.size, client->name,
writable ? "writable" : "read-only", at24->write_max);
if (use_smbus == I2C_SMBUS_WORD_DATA ||
use_smbus == I2C_SMBUS_BYTE_DATA) {
dev_notice(&client->dev, "Falling back to %s reads, "
"performance will suffer\n", use_smbus ==
I2C_SMBUS_WORD_DATA ? "word" : "byte");
}
/* export data to kernel code */
if (chip.setup)
chip.setup(&at24->macc, chip.context);
return 0;
err_clients:
for (i = 1; i < num_addresses; i++)
if (at24->client[i])
i2c_unregister_device(at24->client[i]);
return err;
}
static int at24_remove(struct i2c_client *client)
{
struct at24_data *at24;
int i;
at24 = i2c_get_clientdata(client);
sysfs_remove_bin_file(&client->dev.kobj, &at24->bin);
for (i = 1; i < at24->num_addresses; i++)
i2c_unregister_device(at24->client[i]);
+#ifdef CONFIG_EEPROM_CLASS
+ eeprom_device_unregister(at24->eeprom_dev);
+#endif
+
return 0;
}
/*-------------------------------------------------------------------------*/
static struct i2c_driver at24_driver = {
.driver = {
.name = "at24",
.owner = THIS_MODULE,
},
.probe = at24_probe,
.remove = at24_remove,
.id_table = at24_ids,
};
static int __init at24_init(void)
{
if (!io_limit) {
pr_err("at24: io_limit must not be 0!\n");
return -EINVAL;
}
io_limit = rounddown_pow_of_two(io_limit);
return i2c_add_driver(&at24_driver);
}
module_init(at24_init);
static void __exit at24_exit(void)
{
i2c_del_driver(&at24_driver);
}
module_exit(at24_exit);
MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
MODULE_AUTHOR("David Brownell and Wolfram Sang");
MODULE_LICENSE("GPL");
--
1.7.10.4
^ permalink raw reply related [flat|nested] 8+ messages in thread
end of thread, other threads:[~2014-01-23 19:10 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2014-01-23 7:44 [PATCH 2/2] Add at24 based EEPROMs to the eeprom_dev hardware class Laszlo Papp
2014-01-23 15:05 ` Curt Brune
[not found] ` <20140123150524.GH29955-qUQiAmfTcIp+XZJcv9eMoEEOCMrvLtNR@public.gmane.org>
2014-01-23 17:06 ` Laszlo Papp
2014-01-23 17:25 ` Wolfram Sang
2014-01-23 17:51 ` Laszlo Papp
[not found] ` <CAOMwXhPqnSNWtPMo7Qrr-O3qAqtjju7au7Mudckp7kN50yQW3A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-01-23 18:15 ` Wolfram Sang
2014-01-23 19:10 ` Curt Brune
-- strict thread matches above, loose matches on Subject: below --
2014-01-22 17:47 Curt Brune
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