diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/i2c/busses/i2c-kempld.c | 408 |
1 files changed, 408 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-kempld.c b/drivers/i2c/busses/i2c-kempld.c new file mode 100644 index 000000000..1c874aaa0 --- /dev/null +++ b/drivers/i2c/busses/i2c-kempld.c @@ -0,0 +1,408 @@ +/* + * I2C bus driver for Kontron COM modules + * + * Copyright (c) 2010-2013 Kontron Europe GmbH + * Author: Michael Brunner <michael.brunner@kontron.com> + * + * The driver is based on the i2c-ocores driver by Peter Korsgaard. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License 2 as published + * by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/i2c.h> +#include <linux/delay.h> +#include <linux/mfd/kempld.h> + +#define KEMPLD_I2C_PRELOW 0x0b +#define KEMPLD_I2C_PREHIGH 0x0c +#define KEMPLD_I2C_DATA 0x0e + +#define KEMPLD_I2C_CTRL 0x0d +#define I2C_CTRL_IEN 0x40 +#define I2C_CTRL_EN 0x80 + +#define KEMPLD_I2C_STAT 0x0f +#define I2C_STAT_IF 0x01 +#define I2C_STAT_TIP 0x02 +#define I2C_STAT_ARBLOST 0x20 +#define I2C_STAT_BUSY 0x40 +#define I2C_STAT_NACK 0x80 + +#define KEMPLD_I2C_CMD 0x0f +#define I2C_CMD_START 0x91 +#define I2C_CMD_STOP 0x41 +#define I2C_CMD_READ 0x21 +#define I2C_CMD_WRITE 0x11 +#define I2C_CMD_READ_ACK 0x21 +#define I2C_CMD_READ_NACK 0x29 +#define I2C_CMD_IACK 0x01 + +#define KEMPLD_I2C_FREQ_MAX 2700 /* 2.7 mHz */ +#define KEMPLD_I2C_FREQ_STD 100 /* 100 kHz */ + +enum { + STATE_DONE = 0, + STATE_INIT, + STATE_ADDR, + STATE_ADDR10, + STATE_START, + STATE_WRITE, + STATE_READ, + STATE_ERROR, +}; + +struct kempld_i2c_data { + struct device *dev; + struct kempld_device_data *pld; + struct i2c_adapter adap; + struct i2c_msg *msg; + int pos; + int nmsgs; + int state; + bool was_active; +}; + +static unsigned int bus_frequency = KEMPLD_I2C_FREQ_STD; +module_param(bus_frequency, uint, 0); +MODULE_PARM_DESC(bus_frequency, "Set I2C bus frequency in kHz (default=" + __MODULE_STRING(KEMPLD_I2C_FREQ_STD)")"); + +static int i2c_bus = -1; +module_param(i2c_bus, int, 0); +MODULE_PARM_DESC(i2c_bus, "Set I2C bus number (default=-1 for dynamic assignment)"); + +static bool i2c_gpio_mux; +module_param(i2c_gpio_mux, bool, 0); +MODULE_PARM_DESC(i2c_gpio_mux, "Enable I2C port on GPIO out (default=false)"); + +/* + * kempld_get_mutex must be called prior to calling this function. + */ +static int kempld_i2c_process(struct kempld_i2c_data *i2c) +{ + struct kempld_device_data *pld = i2c->pld; + u8 stat = kempld_read8(pld, KEMPLD_I2C_STAT); + struct i2c_msg *msg = i2c->msg; + u8 addr; + + /* Ready? */ + if (stat & I2C_STAT_TIP) + return -EBUSY; + + if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) { + /* Stop has been sent */ + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK); + if (i2c->state == STATE_ERROR) + return -EIO; + return 0; + } + + /* Error? */ + if (stat & I2C_STAT_ARBLOST) { + i2c->state = STATE_ERROR; + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP); + return -EAGAIN; + } + + if (i2c->state == STATE_INIT) { + if (stat & I2C_STAT_BUSY) + return -EBUSY; + + i2c->state = STATE_ADDR; + } + + if (i2c->state == STATE_ADDR) { + /* 10 bit address? */ + if (i2c->msg->flags & I2C_M_TEN) { + addr = 0xf0 | ((i2c->msg->addr >> 7) & 0x6); + /* Set read bit if necessary */ + addr |= (i2c->msg->flags & I2C_M_RD) ? 1 : 0; + i2c->state = STATE_ADDR10; + } else { + addr = i2c_8bit_addr_from_msg(i2c->msg); + i2c->state = STATE_START; + } + + kempld_write8(pld, KEMPLD_I2C_DATA, addr); + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_START); + + return 0; + } + + /* Second part of 10 bit addressing */ + if (i2c->state == STATE_ADDR10) { + kempld_write8(pld, KEMPLD_I2C_DATA, i2c->msg->addr & 0xff); + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE); + + i2c->state = STATE_START; + return 0; + } + + if (i2c->state == STATE_START || i2c->state == STATE_WRITE) { + i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE; + + if (stat & I2C_STAT_NACK) { + i2c->state = STATE_ERROR; + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP); + return -ENXIO; + } + } else { + msg->buf[i2c->pos++] = kempld_read8(pld, KEMPLD_I2C_DATA); + } + + if (i2c->pos >= msg->len) { + i2c->nmsgs--; + i2c->msg++; + i2c->pos = 0; + msg = i2c->msg; + + if (i2c->nmsgs) { + if (!(msg->flags & I2C_M_NOSTART)) { + i2c->state = STATE_ADDR; + return 0; + } else { + i2c->state = (msg->flags & I2C_M_RD) + ? STATE_READ : STATE_WRITE; + } + } else { + i2c->state = STATE_DONE; + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP); + return 0; + } + } + + if (i2c->state == STATE_READ) { + kempld_write8(pld, KEMPLD_I2C_CMD, i2c->pos == (msg->len - 1) ? + I2C_CMD_READ_NACK : I2C_CMD_READ_ACK); + } else { + kempld_write8(pld, KEMPLD_I2C_DATA, msg->buf[i2c->pos++]); + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE); + } + + return 0; +} + +static int kempld_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, + int num) +{ + struct kempld_i2c_data *i2c = i2c_get_adapdata(adap); + struct kempld_device_data *pld = i2c->pld; + unsigned long timeout = jiffies + HZ; + int ret; + + i2c->msg = msgs; + i2c->pos = 0; + i2c->nmsgs = num; + i2c->state = STATE_INIT; + + /* Handle the transfer */ + while (time_before(jiffies, timeout)) { + kempld_get_mutex(pld); + ret = kempld_i2c_process(i2c); + kempld_release_mutex(pld); + + if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) + return (i2c->state == STATE_DONE) ? num : ret; + + if (ret == 0) + timeout = jiffies + HZ; + + usleep_range(5, 15); + } + + i2c->state = STATE_ERROR; + + return -ETIMEDOUT; +} + +/* + * kempld_get_mutex must be called prior to calling this function. + */ +static void kempld_i2c_device_init(struct kempld_i2c_data *i2c) +{ + struct kempld_device_data *pld = i2c->pld; + u16 prescale_corr; + long prescale; + u8 ctrl; + u8 stat; + u8 cfg; + + /* Make sure the device is disabled */ + ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL); + ctrl &= ~(I2C_CTRL_EN | I2C_CTRL_IEN); + kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl); + + if (bus_frequency > KEMPLD_I2C_FREQ_MAX) + bus_frequency = KEMPLD_I2C_FREQ_MAX; + + if (pld->info.spec_major == 1) + prescale = pld->pld_clock / (bus_frequency * 5) - 1000; + else + prescale = pld->pld_clock / (bus_frequency * 4) - 3000; + + if (prescale < 0) + prescale = 0; + + /* Round to the best matching value */ + prescale_corr = prescale / 1000; + if (prescale % 1000 >= 500) + prescale_corr++; + + kempld_write8(pld, KEMPLD_I2C_PRELOW, prescale_corr & 0xff); + kempld_write8(pld, KEMPLD_I2C_PREHIGH, prescale_corr >> 8); + + /* Activate I2C bus output on GPIO pins */ + cfg = kempld_read8(pld, KEMPLD_CFG); + if (i2c_gpio_mux) + cfg |= KEMPLD_CFG_GPIO_I2C_MUX; + else + cfg &= ~KEMPLD_CFG_GPIO_I2C_MUX; + kempld_write8(pld, KEMPLD_CFG, cfg); + + /* Enable the device */ + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK); + ctrl |= I2C_CTRL_EN; + kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl); + + stat = kempld_read8(pld, KEMPLD_I2C_STAT); + if (stat & I2C_STAT_BUSY) + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP); +} + +static u32 kempld_i2c_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL; +} + +static const struct i2c_algorithm kempld_i2c_algorithm = { + .master_xfer = kempld_i2c_xfer, + .functionality = kempld_i2c_func, +}; + +static const struct i2c_adapter kempld_i2c_adapter = { + .owner = THIS_MODULE, + .name = "i2c-kempld", + .class = I2C_CLASS_HWMON | I2C_CLASS_SPD, + .algo = &kempld_i2c_algorithm, +}; + +static int kempld_i2c_probe(struct platform_device *pdev) +{ + struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent); + struct kempld_i2c_data *i2c; + int ret; + u8 ctrl; + + i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL); + if (!i2c) + return -ENOMEM; + + i2c->pld = pld; + i2c->dev = &pdev->dev; + i2c->adap = kempld_i2c_adapter; + i2c->adap.dev.parent = i2c->dev; + i2c_set_adapdata(&i2c->adap, i2c); + platform_set_drvdata(pdev, i2c); + + kempld_get_mutex(pld); + ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL); + + if (ctrl & I2C_CTRL_EN) + i2c->was_active = true; + + kempld_i2c_device_init(i2c); + kempld_release_mutex(pld); + + /* Add I2C adapter to I2C tree */ + if (i2c_bus >= -1) + i2c->adap.nr = i2c_bus; + ret = i2c_add_numbered_adapter(&i2c->adap); + if (ret) + return ret; + + dev_info(i2c->dev, "I2C bus initialized at %dkHz\n", + bus_frequency); + + return 0; +} + +static int kempld_i2c_remove(struct platform_device *pdev) +{ + struct kempld_i2c_data *i2c = platform_get_drvdata(pdev); + struct kempld_device_data *pld = i2c->pld; + u8 ctrl; + + kempld_get_mutex(pld); + /* + * Disable I2C logic if it was not activated before the + * driver loaded + */ + if (!i2c->was_active) { + ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL); + ctrl &= ~I2C_CTRL_EN; + kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl); + } + kempld_release_mutex(pld); + + i2c_del_adapter(&i2c->adap); + + return 0; +} + +#ifdef CONFIG_PM +static int kempld_i2c_suspend(struct platform_device *pdev, pm_message_t state) +{ + struct kempld_i2c_data *i2c = platform_get_drvdata(pdev); + struct kempld_device_data *pld = i2c->pld; + u8 ctrl; + + kempld_get_mutex(pld); + ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL); + ctrl &= ~I2C_CTRL_EN; + kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl); + kempld_release_mutex(pld); + + return 0; +} + +static int kempld_i2c_resume(struct platform_device *pdev) +{ + struct kempld_i2c_data *i2c = platform_get_drvdata(pdev); + struct kempld_device_data *pld = i2c->pld; + + kempld_get_mutex(pld); + kempld_i2c_device_init(i2c); + kempld_release_mutex(pld); + + return 0; +} +#else +#define kempld_i2c_suspend NULL +#define kempld_i2c_resume NULL +#endif + +static struct platform_driver kempld_i2c_driver = { + .driver = { + .name = "kempld-i2c", + }, + .probe = kempld_i2c_probe, + .remove = kempld_i2c_remove, + .suspend = kempld_i2c_suspend, + .resume = kempld_i2c_resume, +}; + +module_platform_driver(kempld_i2c_driver); + +MODULE_DESCRIPTION("KEM PLD I2C Driver"); +MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:kempld_i2c"); |