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82fa63bd6b
linux/drivers/i2c/busses/i2c-mxs.c
Wolfram Sang 82fa63bd6b i2c: mxs: remove broken PIOQUEUE support 
This I2C master can do DMA and PIOQUEUE (PIO with FIFO). Originally,
only PIOQUEUE was supported and it had issues, then DMA support was added
this cycle. The original intention was to keep PIOQUEUE since it has
less overhead what is nice for small transfers. However, runtime
switching between PIOQEUE and DMA depending on the transfer size never
worked despite a lot of trying. Since PIOQUEUE mode itself was flaky
(polling at places where interrupts failed to work) and the
implementation also imposed a size limit for transfers, it is best to
remove the support, so users don't fall over its limitations. It also
makes the driver a lot cleaner and more robust. If somebody really wants
less overhead, plain PIO mode could still be implemented with the
addidtional advantage that this mode is also available on MX23, too.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Reviewed-by: Marek Vasut <marex@denx.de>
2012-11-02 10:52:32 +01:00

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/*
* Freescale MXS I2C bus driver
*
* Copyright (C) 2011-2012 Wolfram Sang, Pengutronix e.K.
*
* based on a (non-working) driver which was:
*
* Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved.
*
* 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 <linux/pinctrl/consumer.h>
#include <linux/stmp_device.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_i2c.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/fsl/mxs-dma.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_TIMING0 (0x10)
#define MXS_I2C_TIMING1 (0x20)
#define MXS_I2C_TIMING2 (0x30)
#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_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_speed_config {
uint32_t timing0;
uint32_t timing1;
uint32_t timing2;
};
/*
* Timing values for the default 24MHz clock supplied into the i2c block.
*
* The bus can operate at 95kHz or at 400kHz with the following timing
* register configurations. The 100kHz mode isn't present because it's
* values are not stated in the i.MX233/i.MX28 datasheet. The 95kHz mode
* shall be close enough replacement. Therefore when the bus is configured
* for 100kHz operation, 95kHz timing settings are actually loaded.
*
* For details, see i.MX233 [25.4.2 - 25.4.4] and i.MX28 [27.5.2 - 27.5.4].
*/
static const struct mxs_i2c_speed_config mxs_i2c_95kHz_config = {
.timing0 = 0x00780030,
.timing1 = 0x00800030,
.timing2 = 0x00300030,
};
static const struct mxs_i2c_speed_config mxs_i2c_400kHz_config = {
.timing0 = 0x000f0007,
.timing1 = 0x001f000f,
.timing2 = 0x00300030,
};
/**
* 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;
const struct mxs_i2c_speed_config *speed;
/* DMA support components */
int dma_channel;
struct dma_chan *dmach;
struct mxs_dma_data dma_data;
uint32_t pio_data[2];
uint32_t addr_data;
struct scatterlist sg_io[2];
bool dma_read;
};
static void mxs_i2c_reset(struct mxs_i2c_dev *i2c)
{
stmp_reset_block(i2c->regs);
writel(i2c->speed->timing0, i2c->regs + MXS_I2C_TIMING0);
writel(i2c->speed->timing1, i2c->regs + MXS_I2C_TIMING1);
writel(i2c->speed->timing2, i2c->regs + MXS_I2C_TIMING2);
writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
}
static void mxs_i2c_dma_finish(struct mxs_i2c_dev *i2c)
{
if (i2c->dma_read) {
dma_unmap_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
dma_unmap_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
} else {
dma_unmap_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
}
}
static void mxs_i2c_dma_irq_callback(void *param)
{
struct mxs_i2c_dev *i2c = param;
complete(&i2c->cmd_complete);
mxs_i2c_dma_finish(i2c);
}
static int mxs_i2c_dma_setup_xfer(struct i2c_adapter *adap,
struct i2c_msg *msg, uint32_t flags)
{
struct dma_async_tx_descriptor *desc;
struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
if (msg->flags & I2C_M_RD) {
i2c->dma_read = 1;
i2c->addr_data = (msg->addr << 1) | I2C_SMBUS_READ;
/*
* SELECT command.
*/
/* Queue the PIO register write transfer. */
i2c->pio_data[0] = MXS_CMD_I2C_SELECT;
desc = dmaengine_prep_slave_sg(i2c->dmach,
(struct scatterlist *)&i2c->pio_data[0],
1, DMA_TRANS_NONE, 0);
if (!desc) {
dev_err(i2c->dev,
"Failed to get PIO reg. write descriptor.\n");
goto select_init_pio_fail;
}
/* Queue the DMA data transfer. */
sg_init_one(&i2c->sg_io[0], &i2c->addr_data, 1);
dma_map_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[0], 1,
DMA_MEM_TO_DEV,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc) {
dev_err(i2c->dev,
"Failed to get DMA data write descriptor.\n");
goto select_init_dma_fail;
}
/*
* READ command.
*/
/* Queue the PIO register write transfer. */
i2c->pio_data[1] = flags | MXS_CMD_I2C_READ |
MXS_I2C_CTRL0_XFER_COUNT(msg->len);
desc = dmaengine_prep_slave_sg(i2c->dmach,
(struct scatterlist *)&i2c->pio_data[1],
1, DMA_TRANS_NONE, DMA_PREP_INTERRUPT);
if (!desc) {
dev_err(i2c->dev,
"Failed to get PIO reg. write descriptor.\n");
goto select_init_dma_fail;
}
/* Queue the DMA data transfer. */
sg_init_one(&i2c->sg_io[1], msg->buf, msg->len);
dma_map_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[1], 1,
DMA_DEV_TO_MEM,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc) {
dev_err(i2c->dev,
"Failed to get DMA data write descriptor.\n");
goto read_init_dma_fail;
}
} else {
i2c->dma_read = 0;
i2c->addr_data = (msg->addr << 1) | I2C_SMBUS_WRITE;
/*
* WRITE command.
*/
/* Queue the PIO register write transfer. */
i2c->pio_data[0] = flags | MXS_CMD_I2C_WRITE |
MXS_I2C_CTRL0_XFER_COUNT(msg->len + 1);
desc = dmaengine_prep_slave_sg(i2c->dmach,
(struct scatterlist *)&i2c->pio_data[0],
1, DMA_TRANS_NONE, 0);
if (!desc) {
dev_err(i2c->dev,
"Failed to get PIO reg. write descriptor.\n");
goto write_init_pio_fail;
}
/* Queue the DMA data transfer. */
sg_init_table(i2c->sg_io, 2);
sg_set_buf(&i2c->sg_io[0], &i2c->addr_data, 1);
sg_set_buf(&i2c->sg_io[1], msg->buf, msg->len);
dma_map_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
desc = dmaengine_prep_slave_sg(i2c->dmach, i2c->sg_io, 2,
DMA_MEM_TO_DEV,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc) {
dev_err(i2c->dev,
"Failed to get DMA data write descriptor.\n");
goto write_init_dma_fail;
}
}
/*
* The last descriptor must have this callback,
* to finish the DMA transaction.
*/
desc->callback = mxs_i2c_dma_irq_callback;
desc->callback_param = i2c;
/* Start the transfer. */
dmaengine_submit(desc);
dma_async_issue_pending(i2c->dmach);
return 0;
/* Read failpath. */
read_init_dma_fail:
dma_unmap_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
select_init_dma_fail:
dma_unmap_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
select_init_pio_fail:
return -EINVAL;
/* Write failpath. */
write_init_dma_fail:
dma_unmap_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
write_init_pio_fail:
return -EINVAL;
}
/*
* 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;
flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0;
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;
init_completion(&i2c->cmd_complete);
i2c->cmd_err = 0;
ret = mxs_i2c_dma_setup_xfer(adap, msg, flags);
if (ret)
return ret;
ret = wait_for_completion_timeout(&i2c->cmd_complete,
msecs_to_jiffies(1000));
if (ret == 0)
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_dma_finish(i2c);
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;
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 bool mxs_i2c_dma_filter(struct dma_chan *chan, void *param)
{
struct mxs_i2c_dev *i2c = param;
if (!mxs_dma_is_apbx(chan))
return false;
if (chan->chan_id != i2c->dma_channel)
return false;
chan->private = &i2c->dma_data;
return true;
}
static int mxs_i2c_get_ofdata(struct mxs_i2c_dev *i2c)
{
uint32_t speed;
struct device *dev = i2c->dev;
struct device_node *node = dev->of_node;
int ret;
/*
* TODO: This is a temporary solution and should be changed
* to use generic DMA binding later when the helpers get in.
*/
ret = of_property_read_u32(node, "fsl,i2c-dma-channel",
&i2c->dma_channel);
if (ret) {
dev_err(dev, "Failed to get DMA channel!\n");
return -ENODEV;
}
ret = of_property_read_u32(node, "clock-frequency", &speed);
if (ret)
dev_warn(dev, "No I2C speed selected, using 100kHz\n");
else if (speed == 400000)
i2c->speed = &mxs_i2c_400kHz_config;
else if (speed != 100000)
dev_warn(dev, "Unsupported I2C speed selected, using 100kHz\n");
return 0;
}
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 pinctrl *pinctrl;
struct resource *res;
resource_size_t res_size;
int err, irq, dmairq;
dma_cap_mask_t mask;
pinctrl = devm_pinctrl_get_select_default(dev);
if (IS_ERR(pinctrl))
return PTR_ERR(pinctrl);
i2c = devm_kzalloc(dev, sizeof(struct mxs_i2c_dev), GFP_KERNEL);
if (!i2c)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
irq = platform_get_irq(pdev, 0);
dmairq = platform_get_irq(pdev, 1);
if (!res || irq < 0 || dmairq < 0)
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;
err = devm_request_irq(dev, irq, mxs_i2c_isr, 0, dev_name(dev), i2c);
if (err)
return err;
i2c->dev = dev;
i2c->speed = &mxs_i2c_95kHz_config;
if (dev->of_node) {
err = mxs_i2c_get_ofdata(i2c);
if (err)
return err;
}
/* Setup the DMA */
dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);
i2c->dma_data.chan_irq = dmairq;
i2c->dmach = dma_request_channel(mask, mxs_i2c_dma_filter, i2c);
if (!i2c->dmach) {
dev_err(dev, "Failed to request dma\n");
return -ENODEV;
}
platform_set_drvdata(pdev, i2c);
/* Do reset to enforce correct startup after pinmuxing */
mxs_i2c_reset(i2c);
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;
adap->dev.of_node = pdev->dev.of_node;
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;
}
of_i2c_register_devices(adap);
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;
if (i2c->dmach)
dma_release_channel(i2c->dmach);
writel(MXS_I2C_CTRL0_SFTRST, i2c->regs + MXS_I2C_CTRL0_SET);
platform_set_drvdata(pdev, NULL);
return 0;
}
static const struct of_device_id mxs_i2c_dt_ids[] = {
{ .compatible = "fsl,imx28-i2c", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, mxs_i2c_dt_ids);
static struct platform_driver mxs_i2c_driver = {
.driver = {
.name = DRIVER_NAME,
.owner = THIS_MODULE,
.of_match_table = mxs_i2c_dt_ids,
},
.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);
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