Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755415AbaKRQD4 (ORCPT ); Tue, 18 Nov 2014 11:03:56 -0500 Received: from sauhun.de ([89.238.76.85]:46110 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755244AbaKRQDw (ORCPT ); Tue, 18 Nov 2014 11:03:52 -0500 From: Wolfram Sang To: linux-i2c@vger.kernel.org Cc: linux-sh@vger.kernel.org, Wolfram Sang , Magnus Damm , Simon Horman , Laurent Pinchart , Geert Uytterhoeven , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Jean Delvare Subject: [PATCH 2/3] i2c: slave-eeprom: add eeprom simulator driver Date: Tue, 18 Nov 2014 17:04:54 +0100 Message-Id: <1416326695-13083-3-git-send-email-wsa@the-dreams.de> X-Mailer: git-send-email 2.1.1 In-Reply-To: <1416326695-13083-1-git-send-email-wsa@the-dreams.de> References: <1416326695-13083-1-git-send-email-wsa@the-dreams.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wolfram Sang The first user of the i2c-slave interface is an eeprom simulator. It is a shared memory which can be accessed by the remote master via I2C and locally via sysfs. Signed-off-by: Wolfram Sang --- Changes since RFC: * fix build error for modules * don't hardcode size * add boundary checks for sysfs access * use a spinlock * s/at24s/eeprom/g * add some docs * clean up exit paths * use size-variable instead of driver_data drivers/i2c/Kconfig | 10 +++ drivers/i2c/Makefile | 1 + drivers/i2c/i2c-slave-eeprom.c | 170 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 181 insertions(+) create mode 100644 drivers/i2c/i2c-slave-eeprom.c diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig index b51a402752c4..8c9e619f3026 100644 --- a/drivers/i2c/Kconfig +++ b/drivers/i2c/Kconfig @@ -110,6 +110,16 @@ config I2C_STUB If you don't know what to do here, definitely say N. +config I2C_SLAVE + bool "I2C slave support" + +if I2C_SLAVE + +config I2C_SLAVE_EEPROM + tristate "I2C eeprom slave driver" + +endif + config I2C_DEBUG_CORE bool "I2C Core debugging messages" help diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile index 1722f50f2473..45095b3d16a9 100644 --- a/drivers/i2c/Makefile +++ b/drivers/i2c/Makefile @@ -9,6 +9,7 @@ obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o obj-$(CONFIG_I2C_MUX) += i2c-mux.o obj-y += algos/ busses/ muxes/ obj-$(CONFIG_I2C_STUB) += i2c-stub.o +obj-$(CONFIG_I2C_SLAVE_EEPROM) += i2c-slave-eeprom.o ccflags-$(CONFIG_I2C_DEBUG_CORE) := -DDEBUG CFLAGS_i2c-core.o := -Wno-deprecated-declarations diff --git a/drivers/i2c/i2c-slave-eeprom.c b/drivers/i2c/i2c-slave-eeprom.c new file mode 100644 index 000000000000..6631400b5f02 --- /dev/null +++ b/drivers/i2c/i2c-slave-eeprom.c @@ -0,0 +1,170 @@ +/* + * I2C slave mode EEPROM simulator + * + * Copyright (C) 2014 by Wolfram Sang, Sang Engineering + * Copyright (C) 2014 by Renesas Electronics Corporation + * + * 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; version 2 of the License. + * + * Because most IP blocks can only detect one I2C slave address anyhow, this + * driver does not support simulating EEPROM types which take more than one + * address. It is prepared to simulate bigger EEPROMs with an internal 16 bit + * pointer, yet implementation is deferred until the need actually arises. + */ + +#include +#include +#include +#include +#include +#include +#include + +struct eeprom_data { + struct bin_attribute bin; + bool first_write; + spinlock_t buffer_lock; + u8 buffer_idx; + u8 buffer[]; +}; + +static int i2c_slave_eeprom_slave_cb(struct i2c_client *client, + enum i2c_slave_event event, u8 *val) +{ + struct eeprom_data *eeprom = i2c_get_clientdata(client); + + switch (event) { + case I2C_SLAVE_REQ_WRITE_END: + if (eeprom->first_write) { + eeprom->buffer_idx = *val; + eeprom->first_write = false; + } else { + spin_lock(&eeprom->buffer_lock); + eeprom->buffer[eeprom->buffer_idx++] = *val; + spin_unlock(&eeprom->buffer_lock); + } + break; + + case I2C_SLAVE_REQ_READ_START: + spin_lock(&eeprom->buffer_lock); + *val = eeprom->buffer[eeprom->buffer_idx]; + spin_unlock(&eeprom->buffer_lock); + break; + + case I2C_SLAVE_REQ_READ_END: + eeprom->buffer_idx++; + break; + + case I2C_SLAVE_STOP: + eeprom->first_write = true; + break; + + default: + break; + } + + return 0; +} + +static ssize_t i2c_slave_eeprom_bin_read(struct file *filp, struct kobject *kobj, + struct bin_attribute *attr, char *buf, loff_t off, size_t count) +{ + struct eeprom_data *eeprom; + unsigned long flags; + + if (off + count >= attr->size) + return -EFBIG; + + eeprom = dev_get_drvdata(container_of(kobj, struct device, kobj)); + + spin_lock_irqsave(&eeprom->buffer_lock, flags); + memcpy(buf, &eeprom->buffer[off], count); + spin_unlock_irqrestore(&eeprom->buffer_lock, flags); + + return count; +} + +static ssize_t i2c_slave_eeprom_bin_write(struct file *filp, struct kobject *kobj, + struct bin_attribute *attr, char *buf, loff_t off, size_t count) +{ + struct eeprom_data *eeprom; + unsigned long flags; + + if (off + count >= attr->size) + return -EFBIG; + + eeprom = dev_get_drvdata(container_of(kobj, struct device, kobj)); + + spin_lock_irqsave(&eeprom->buffer_lock, flags); + memcpy(&eeprom->buffer[off], buf, count); + spin_unlock_irqrestore(&eeprom->buffer_lock, flags); + + return count; +} + +static int i2c_slave_eeprom_probe(struct i2c_client *client, const struct i2c_device_id *id) +{ + struct eeprom_data *eeprom; + int ret; + unsigned size = id->driver_data; + + eeprom = devm_kzalloc(&client->dev, sizeof(struct eeprom_data) + size, GFP_KERNEL); + if (!eeprom) + return -ENOMEM; + + eeprom->first_write = true; + spin_lock_init(&eeprom->buffer_lock); + i2c_set_clientdata(client, eeprom); + + sysfs_bin_attr_init(&eeprom->bin); + eeprom->bin.attr.name = "slave-eeprom"; + eeprom->bin.attr.mode = S_IRUSR | S_IWUSR; + eeprom->bin.read = i2c_slave_eeprom_bin_read; + eeprom->bin.write = i2c_slave_eeprom_bin_write; + eeprom->bin.size = size; + + ret = sysfs_create_bin_file(&client->dev.kobj, &eeprom->bin); + if (ret) + return ret; + + ret = i2c_slave_register(client, i2c_slave_eeprom_slave_cb); + if (ret) { + sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin); + return ret; + } + + return 0; +}; + +static int i2c_slave_eeprom_remove(struct i2c_client *client) +{ + struct eeprom_data *eeprom = i2c_get_clientdata(client); + + i2c_slave_unregister(client); + sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin); + + return 0; +} + +static const struct i2c_device_id i2c_slave_eeprom_id[] = { + { "slave-24c02", 2048 / 8 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, i2c_slave_eeprom_id); + +static struct i2c_driver i2c_slave_eeprom_driver = { + .driver = { + .name = "i2c-slave-eeprom", + .owner = THIS_MODULE, + }, + .probe = i2c_slave_eeprom_probe, + .remove = i2c_slave_eeprom_remove, + .id_table = i2c_slave_eeprom_id, +}; +module_i2c_driver(i2c_slave_eeprom_driver); + +MODULE_AUTHOR("Wolfram Sang "); +MODULE_DESCRIPTION("I2C slave mode EEPROM simulator"); +MODULE_LICENSE("GPL v2"); -- 2.1.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/