From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754312AbdLTI07 (ORCPT ); Wed, 20 Dec 2017 03:26:59 -0500 Received: from mail-wr0-f195.google.com ([209.85.128.195]:35093 "EHLO mail-wr0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754594AbdLTI0l (ORCPT ); Wed, 20 Dec 2017 03:26:41 -0500 X-Google-Smtp-Source: ACJfBotPjofyqmjqd7eFYP7LZ1C4WctXvxxvL8bTle6vgW+j7QTqnQKrblWnRXeihiWOVzm/j2JqMA== From: Bartosz Golaszewski To: Andy Shevchenko , Rob Herring , Mark Rutland , Linus Walleij , Peter Rosin Cc: linux-i2c@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski Subject: [PATCH v2 2/2] eeprom: at24: add support for the write-protect pin Date: Wed, 20 Dec 2017 09:26:33 +0100 Message-Id: <20171220082633.32237-3-brgl@bgdev.pl> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171220082633.32237-1-brgl@bgdev.pl> References: <20171220082633.32237-1-brgl@bgdev.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org AT24 EEPROMs have a write-protect pin, which - when pulled high - inhibits writes to the upper quadrant of memory (although it has been observed that on some chips it disables writing to the entire memory range). On some boards, this pin is connected to a GPIO and pulled high by default, which forces the user to manually change its state before writing. On linux this means that we either need to hog the line all the time, or set the GPIO value before writing from outside of the at24 driver. Make the driver check if the write-protect GPIO was defined in the device tree and pull it low whenever writing to the EEPROM. Signed-off-by: Bartosz Golaszewski --- drivers/misc/eeprom/at24.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c index b44a3d2b2b20..4456e192681c 100644 --- a/drivers/misc/eeprom/at24.c +++ b/drivers/misc/eeprom/at24.c @@ -27,6 +27,7 @@ #include #include #include +#include /* * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable. @@ -77,6 +78,8 @@ struct at24_data { struct nvmem_config nvmem_config; struct nvmem_device *nvmem; + struct gpio_desc *wp_gpio; + /* * Some chips tie up multiple I2C addresses; dummy devices reserve * them for us, and we'll use them with SMBus calls. @@ -442,12 +445,14 @@ static int at24_write(void *priv, unsigned int off, void *val, size_t count) * from this host, but not from other I2C masters. */ mutex_lock(&at24->lock); + gpiod_set_value_cansleep(at24->wp_gpio, 0); while (count) { int status; status = at24_regmap_write(at24, buf, off, count); if (status < 0) { + gpiod_set_value_cansleep(at24->wp_gpio, 1); mutex_unlock(&at24->lock); pm_runtime_put(dev); return status; @@ -457,6 +462,7 @@ static int at24_write(void *priv, unsigned int off, void *val, size_t count) count -= status; } + gpiod_set_value_cansleep(at24->wp_gpio, 1); mutex_unlock(&at24->lock); pm_runtime_put(dev); @@ -604,6 +610,11 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id) at24->num_addresses = num_addresses; at24->offset_adj = at24_get_offset_adj(chip.flags, chip.byte_len); + at24->wp_gpio = devm_gpiod_get_optional(&client->dev, + "wp", GPIOD_OUT_HIGH); + if (IS_ERR(at24->wp_gpio)) + return PTR_ERR(at24->wp_gpio); + at24->client[0].client = client; at24->client[0].regmap = devm_regmap_init_i2c(client, ®map_config); if (IS_ERR(at24->client[0].regmap)) -- 2.15.1