From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
To: Wolfram Sang <wsa@the-dreams.de>,
linux-i2c <linux-i2c@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>, Andrew Lunn <andrew@lunn.ch>,
Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
Maxime Ripard <maxime.ripard@free-electrons.com>,
GregKH <greg@kroah.com>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Subject: [RESEND PATCH 10/14] eeprom: at24: support reading the serial number
Date: Mon, 6 Jun 2016 10:48:52 +0200 [thread overview]
Message-ID: <1465202936-16832-11-git-send-email-bgolaszewski@baylibre.com> (raw)
In-Reply-To: <1465202936-16832-1-git-send-email-bgolaszewski@baylibre.com>
The at24cs series EEPROM chips have an additional read-only memory area
containing a factory pre-programmed serial number. In order to access
it, one has to perform a dummy write before reading the serial number
bytes.
Add a function that allows to access the serial number and assign it
to at24->read_func if the chip allows serial number read operations
and the driver was passed the relevant flag for this device.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
drivers/misc/eeprom/at24.c | 62 ++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 60 insertions(+), 2 deletions(-)
diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 6acf35a..29bbdad 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -276,6 +276,59 @@ static ssize_t at24_eeprom_read_i2c(struct at24_data *at24, char *buf,
return -ETIMEDOUT;
}
+static ssize_t at24_eeprom_read_serial(struct at24_data *at24, char *buf,
+ unsigned int offset, size_t count)
+{
+ unsigned long timeout, read_time;
+ struct i2c_client *client;
+ struct i2c_msg msg[2];
+ u8 addrbuf[2];
+ int status;
+
+ client = at24_translate_offset(at24, &offset);
+
+ memset(msg, 0, sizeof(msg));
+ msg[0].addr = client->addr;
+ msg[0].buf = addrbuf;
+
+ /*
+ * The address pointer of the device is shared between the regular
+ * EEPROM array and the serial number block. The dummy write (part of
+ * the sequential read protocol) ensures the address pointer is reset
+ * to the desired position.
+ */
+ if (at24->chip.flags & AT24_FLAG_ADDR16) {
+ /*
+ * For 16 bit address pointers, the word address must contain
+ * a '10' sequence in bits 11 and 10 regardless of the
+ * intended position of the address pointer.
+ */
+ addrbuf[0] = 0x08;
+ addrbuf[1] = offset;
+ msg[0].len = 2;
+ } else {
+ /*
+ * Otherwise the word address must begin with a '10' sequence,
+ * regardless of the intended address.
+ */
+ addrbuf[0] = 0x80 + offset;
+ msg[0].len = 1;
+ }
+
+ msg[1].addr = client->addr;
+ msg[1].flags = I2C_M_RD;
+ msg[1].buf = buf;
+ msg[1].len = count;
+
+ loop_until_timeout(timeout, read_time) {
+ status = i2c_transfer(client->adapter, msg, 2);
+ if (status == 2)
+ return count;
+ }
+
+ return -ETIMEDOUT;
+}
+
/*
* Note that if the hardware write-protect pin is pulled high, the whole
* chip is normally write protected. But there are plenty of product
@@ -577,8 +630,13 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
at24->chip = chip;
at24->num_addresses = num_addresses;
- at24->read_func = at24->use_smbus ? at24_eeprom_read_smbus
- : at24_eeprom_read_i2c;
+ if (chip.flags & AT24_FLAG_SERIAL) {
+ at24->read_func = at24_eeprom_read_serial;
+ } else {
+ at24->read_func = at24->use_smbus ? at24_eeprom_read_smbus
+ : at24_eeprom_read_i2c;
+ }
+
if (at24->use_smbus) {
if (at24->use_smbus_write == I2C_SMBUS_I2C_BLOCK_DATA)
at24->write_func = at24_eeprom_write_smbus_block;
--
2.7.4
next prev parent reply other threads:[~2016-06-06 8:49 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-06 8:48 [RESEND PATCH 00/14] eeprom: at24: driver rework and at24cs/at24mac support Bartosz Golaszewski
2016-06-06 8:48 ` [RESEND PATCH 01/14] eeprom: at24: improve the device_id table readability Bartosz Golaszewski
2016-06-06 8:48 ` [RESEND PATCH 02/14] eeprom: at24: move at24_read() below at24_eeprom_write() Bartosz Golaszewski
2016-06-06 8:48 ` [RESEND PATCH 03/14] eeprom: at24: coding style fixes Bartosz Golaszewski
2016-06-06 8:48 ` [RESEND PATCH 04/14] eeprom: at24: call read/write functions via function pointers Bartosz Golaszewski
2016-06-06 8:48 ` [RESEND PATCH 05/14] eeprom: at24: hide the read/write loop behind a macro Bartosz Golaszewski
2016-07-15 12:24 ` Wolfram Sang
2016-07-15 12:49 ` Bartosz Golaszewski
2016-07-15 15:03 ` Wolfram Sang
2016-07-16 4:56 ` Wolfram Sang
2016-07-16 19:25 ` Bartosz Golaszewski
2016-07-17 18:00 ` Wolfram Sang
2016-06-06 8:48 ` [RESEND PATCH 06/14] eeprom: at24: split at24_eeprom_read() into specialized functions Bartosz Golaszewski
2016-06-06 8:48 ` [RESEND PATCH 07/14] eeprom: at24: split at24_eeprom_write() " Bartosz Golaszewski
2016-06-06 8:48 ` [RESEND PATCH 08/14] eeprom: at24: platform_data: use BIT() macro Bartosz Golaszewski
2016-06-06 8:48 ` [RESEND PATCH 09/14] eeprom: at24: platform_data: add serial number flag Bartosz Golaszewski
2016-06-06 8:48 ` Bartosz Golaszewski [this message]
2016-06-06 8:48 ` [RESEND PATCH 11/14] eeprom: at24: add the at24cs series to the list of supported devices Bartosz Golaszewski
2016-07-15 6:30 ` Wolfram Sang
2016-07-15 8:54 ` Bartosz Golaszewski
2016-06-06 8:48 ` [RESEND PATCH 12/14] eeprom: at24: platform_data: add at24mac series flag Bartosz Golaszewski
2016-06-06 8:48 ` [RESEND PATCH 13/14] eeprom: at24: add support for at24mac series Bartosz Golaszewski
2016-06-06 8:48 ` [RESEND PATCH 14/14] eeprom: at24: add at24mac chips to the list of supported devices Bartosz Golaszewski
2016-06-06 11:13 ` [RESEND PATCH 00/14] eeprom: at24: driver rework and at24cs/at24mac support Wolfram Sang
2016-06-06 13:01 ` Bartosz Golaszewski
2016-06-08 8:45 ` Wolfram Sang
2016-06-08 9:22 ` Bartosz Golaszewski
2016-07-17 18:02 ` Wolfram Sang
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