diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-mxs.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-mxs.c | 412 |
1 files changed, 412 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-mxs.c b/drivers/i2c/busses/i2c-mxs.c new file mode 100644 index 00000000000..8022e2390a5 --- /dev/null +++ b/drivers/i2c/busses/i2c-mxs.c @@ -0,0 +1,412 @@ +/* + * Freescale MXS I2C bus driver + * + * Copyright (C) 2011 Wolfram Sang, Pengutronix e.K. + * + * based on a (non-working) driver which was: + * + * Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved. + * + * TODO: add dma-support if platform-support for it is available + * + * 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/slab.h> +#include <linux/device.h> +#include <linux/module.h> +#include <linux/i2c.h> +#include <linux/err.h> +#include <linux/interrupt.h> +#include <linux/completion.h> +#include <linux/platform_device.h> +#include <linux/jiffies.h> +#include <linux/io.h> + +#include <mach/common.h> + +#define DRIVER_NAME "mxs-i2c" + +#define MXS_I2C_CTRL0 (0x00) +#define MXS_I2C_CTRL0_SET (0x04) + +#define MXS_I2C_CTRL0_SFTRST 0x80000000 +#define MXS_I2C_CTRL0_SEND_NAK_ON_LAST 0x02000000 +#define MXS_I2C_CTRL0_RETAIN_CLOCK 0x00200000 +#define MXS_I2C_CTRL0_POST_SEND_STOP 0x00100000 +#define MXS_I2C_CTRL0_PRE_SEND_START 0x00080000 +#define MXS_I2C_CTRL0_MASTER_MODE 0x00020000 +#define MXS_I2C_CTRL0_DIRECTION 0x00010000 +#define MXS_I2C_CTRL0_XFER_COUNT(v) ((v) & 0x0000FFFF) + +#define MXS_I2C_CTRL1 (0x40) +#define MXS_I2C_CTRL1_SET (0x44) +#define MXS_I2C_CTRL1_CLR (0x48) + +#define MXS_I2C_CTRL1_BUS_FREE_IRQ 0x80 +#define MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ 0x40 +#define MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ 0x20 +#define MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ 0x10 +#define MXS_I2C_CTRL1_EARLY_TERM_IRQ 0x08 +#define MXS_I2C_CTRL1_MASTER_LOSS_IRQ 0x04 +#define MXS_I2C_CTRL1_SLAVE_STOP_IRQ 0x02 +#define MXS_I2C_CTRL1_SLAVE_IRQ 0x01 + +#define MXS_I2C_IRQ_MASK (MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ | \ + MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ | \ + MXS_I2C_CTRL1_EARLY_TERM_IRQ | \ + MXS_I2C_CTRL1_MASTER_LOSS_IRQ | \ + MXS_I2C_CTRL1_SLAVE_STOP_IRQ | \ + MXS_I2C_CTRL1_SLAVE_IRQ) + +#define MXS_I2C_QUEUECTRL (0x60) +#define MXS_I2C_QUEUECTRL_SET (0x64) +#define MXS_I2C_QUEUECTRL_CLR (0x68) + +#define MXS_I2C_QUEUECTRL_QUEUE_RUN 0x20 +#define MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE 0x04 + +#define MXS_I2C_QUEUESTAT (0x70) +#define MXS_I2C_QUEUESTAT_RD_QUEUE_EMPTY 0x00002000 + +#define MXS_I2C_QUEUECMD (0x80) + +#define MXS_I2C_QUEUEDATA (0x90) + +#define MXS_I2C_DATA (0xa0) + + +#define MXS_CMD_I2C_SELECT (MXS_I2C_CTRL0_RETAIN_CLOCK | \ + MXS_I2C_CTRL0_PRE_SEND_START | \ + MXS_I2C_CTRL0_MASTER_MODE | \ + MXS_I2C_CTRL0_DIRECTION | \ + MXS_I2C_CTRL0_XFER_COUNT(1)) + +#define MXS_CMD_I2C_WRITE (MXS_I2C_CTRL0_PRE_SEND_START | \ + MXS_I2C_CTRL0_MASTER_MODE | \ + MXS_I2C_CTRL0_DIRECTION) + +#define MXS_CMD_I2C_READ (MXS_I2C_CTRL0_SEND_NAK_ON_LAST | \ + MXS_I2C_CTRL0_MASTER_MODE) + +/** + * struct mxs_i2c_dev - per device, private MXS-I2C data + * + * @dev: driver model device node + * @regs: IO registers pointer + * @cmd_complete: completion object for transaction wait + * @cmd_err: error code for last transaction + * @adapter: i2c subsystem adapter node + */ +struct mxs_i2c_dev { + struct device *dev; + void __iomem *regs; + struct completion cmd_complete; + u32 cmd_err; + struct i2c_adapter adapter; +}; + +/* + * TODO: check if calls to here are really needed. If not, we could get rid of + * mxs_reset_block and the mach-dependency. Needs an I2C analyzer, probably. + */ +static void mxs_i2c_reset(struct mxs_i2c_dev *i2c) +{ + mxs_reset_block(i2c->regs); + writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET); +} + +static void mxs_i2c_pioq_setup_read(struct mxs_i2c_dev *i2c, u8 addr, int len, + int flags) +{ + u32 data; + + writel(MXS_CMD_I2C_SELECT, i2c->regs + MXS_I2C_QUEUECMD); + + data = (addr << 1) | I2C_SMBUS_READ; + writel(data, i2c->regs + MXS_I2C_DATA); + + data = MXS_CMD_I2C_READ | MXS_I2C_CTRL0_XFER_COUNT(len) | flags; + writel(data, i2c->regs + MXS_I2C_QUEUECMD); +} + +static void mxs_i2c_pioq_setup_write(struct mxs_i2c_dev *i2c, + u8 addr, u8 *buf, int len, int flags) +{ + u32 data; + int i, shifts_left; + + data = MXS_CMD_I2C_WRITE | MXS_I2C_CTRL0_XFER_COUNT(len + 1) | flags; + writel(data, i2c->regs + MXS_I2C_QUEUECMD); + + /* + * We have to copy the slave address (u8) and buffer (arbitrary number + * of u8) into the data register (u32). To achieve that, the u8 are put + * into the MSBs of 'data' which is then shifted for the next u8. When + * apropriate, 'data' is written to MXS_I2C_DATA. So, the first u32 + * looks like this: + * + * 3 2 1 0 + * 10987654|32109876|54321098|76543210 + * --------+--------+--------+-------- + * buffer+2|buffer+1|buffer+0|slave_addr + */ + + data = ((addr << 1) | I2C_SMBUS_WRITE) << 24; + + for (i = 0; i < len; i++) { + data >>= 8; + data |= buf[i] << 24; + if ((i & 3) == 2) + writel(data, i2c->regs + MXS_I2C_DATA); + } + + /* Write out the remaining bytes if any */ + shifts_left = 24 - (i & 3) * 8; + if (shifts_left) + writel(data >> shifts_left, i2c->regs + MXS_I2C_DATA); +} + +/* + * TODO: should be replaceable with a waitqueue and RD_QUEUE_IRQ (setting the + * rd_threshold to 1). Couldn't get this to work, though. + */ +static int mxs_i2c_wait_for_data(struct mxs_i2c_dev *i2c) +{ + unsigned long timeout = jiffies + msecs_to_jiffies(1000); + + while (readl(i2c->regs + MXS_I2C_QUEUESTAT) + & MXS_I2C_QUEUESTAT_RD_QUEUE_EMPTY) { + if (time_after(jiffies, timeout)) + return -ETIMEDOUT; + cond_resched(); + } + + return 0; +} + +static int mxs_i2c_finish_read(struct mxs_i2c_dev *i2c, u8 *buf, int len) +{ + u32 data; + int i; + + for (i = 0; i < len; i++) { + if ((i & 3) == 0) { + if (mxs_i2c_wait_for_data(i2c)) + return -ETIMEDOUT; + data = readl(i2c->regs + MXS_I2C_QUEUEDATA); + } + buf[i] = data & 0xff; + data >>= 8; + } + + return 0; +} + +/* + * Low level master read/write transaction. + */ +static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, + int stop) +{ + struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap); + int ret; + int flags; + + init_completion(&i2c->cmd_complete); + + dev_dbg(i2c->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n", + msg->addr, msg->len, msg->flags, stop); + + if (msg->len == 0) + return -EINVAL; + + flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0; + + if (msg->flags & I2C_M_RD) + mxs_i2c_pioq_setup_read(i2c, msg->addr, msg->len, flags); + else + mxs_i2c_pioq_setup_write(i2c, msg->addr, msg->buf, msg->len, + flags); + + writel(MXS_I2C_QUEUECTRL_QUEUE_RUN, + i2c->regs + MXS_I2C_QUEUECTRL_SET); + + ret = wait_for_completion_timeout(&i2c->cmd_complete, + msecs_to_jiffies(1000)); + if (ret == 0) + goto timeout; + + if ((!i2c->cmd_err) && (msg->flags & I2C_M_RD)) { + ret = mxs_i2c_finish_read(i2c, msg->buf, msg->len); + if (ret) + goto timeout; + } + + if (i2c->cmd_err == -ENXIO) + mxs_i2c_reset(i2c); + + dev_dbg(i2c->dev, "Done with err=%d\n", i2c->cmd_err); + + return i2c->cmd_err; + +timeout: + dev_dbg(i2c->dev, "Timeout!\n"); + mxs_i2c_reset(i2c); + return -ETIMEDOUT; +} + +static int mxs_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], + int num) +{ + int i; + int err; + + for (i = 0; i < num; i++) { + err = mxs_i2c_xfer_msg(adap, &msgs[i], i == (num - 1)); + if (err) + return err; + } + + return num; +} + +static u32 mxs_i2c_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK); +} + +static irqreturn_t mxs_i2c_isr(int this_irq, void *dev_id) +{ + struct mxs_i2c_dev *i2c = dev_id; + u32 stat = readl(i2c->regs + MXS_I2C_CTRL1) & MXS_I2C_IRQ_MASK; + + if (!stat) + return IRQ_NONE; + + if (stat & MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ) + i2c->cmd_err = -ENXIO; + else if (stat & (MXS_I2C_CTRL1_EARLY_TERM_IRQ | + MXS_I2C_CTRL1_MASTER_LOSS_IRQ | + MXS_I2C_CTRL1_SLAVE_STOP_IRQ | MXS_I2C_CTRL1_SLAVE_IRQ)) + /* MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ is only for slaves */ + i2c->cmd_err = -EIO; + else + i2c->cmd_err = 0; + + complete(&i2c->cmd_complete); + + writel(stat, i2c->regs + MXS_I2C_CTRL1_CLR); + return IRQ_HANDLED; +} + +static const struct i2c_algorithm mxs_i2c_algo = { + .master_xfer = mxs_i2c_xfer, + .functionality = mxs_i2c_func, +}; + +static int __devinit mxs_i2c_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct mxs_i2c_dev *i2c; + struct i2c_adapter *adap; + struct resource *res; + resource_size_t res_size; + int err, irq; + + i2c = devm_kzalloc(dev, sizeof(struct mxs_i2c_dev), GFP_KERNEL); + if (!i2c) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!res) + return -ENOENT; + + res_size = resource_size(res); + if (!devm_request_mem_region(dev, res->start, res_size, res->name)) + return -EBUSY; + + i2c->regs = devm_ioremap_nocache(dev, res->start, res_size); + if (!i2c->regs) + return -EBUSY; + + irq = platform_get_irq(pdev, 0); + if (irq < 0) + return irq; + + err = devm_request_irq(dev, irq, mxs_i2c_isr, 0, dev_name(dev), i2c); + if (err) + return err; + + i2c->dev = dev; + platform_set_drvdata(pdev, i2c); + + /* Do reset to enforce correct startup after pinmuxing */ + mxs_i2c_reset(i2c); + writel(MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE, + i2c->regs + MXS_I2C_QUEUECTRL_SET); + + adap = &i2c->adapter; + strlcpy(adap->name, "MXS I2C adapter", sizeof(adap->name)); + adap->owner = THIS_MODULE; + adap->algo = &mxs_i2c_algo; + adap->dev.parent = dev; + adap->nr = pdev->id; + i2c_set_adapdata(adap, i2c); + err = i2c_add_numbered_adapter(adap); + if (err) { + dev_err(dev, "Failed to add adapter (%d)\n", err); + writel(MXS_I2C_CTRL0_SFTRST, + i2c->regs + MXS_I2C_CTRL0_SET); + return err; + } + + return 0; +} + +static int __devexit mxs_i2c_remove(struct platform_device *pdev) +{ + struct mxs_i2c_dev *i2c = platform_get_drvdata(pdev); + int ret; + + ret = i2c_del_adapter(&i2c->adapter); + if (ret) + return -EBUSY; + + writel(MXS_I2C_QUEUECTRL_QUEUE_RUN, + i2c->regs + MXS_I2C_QUEUECTRL_CLR); + writel(MXS_I2C_CTRL0_SFTRST, i2c->regs + MXS_I2C_CTRL0_SET); + + platform_set_drvdata(pdev, NULL); + + return 0; +} + +static struct platform_driver mxs_i2c_driver = { + .driver = { + .name = DRIVER_NAME, + .owner = THIS_MODULE, + }, + .remove = __devexit_p(mxs_i2c_remove), +}; + +static int __init mxs_i2c_init(void) +{ + return platform_driver_probe(&mxs_i2c_driver, mxs_i2c_probe); +} +subsys_initcall(mxs_i2c_init); + +static void __exit mxs_i2c_exit(void) +{ + platform_driver_unregister(&mxs_i2c_driver); +} +module_exit(mxs_i2c_exit); + +MODULE_AUTHOR("Wolfram Sang <w.sang@pengutronix.de>"); +MODULE_DESCRIPTION("MXS I2C Bus Driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:" DRIVER_NAME); |