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linux/drivers/i2c/busses/i2c-xlr.c
Måns Rullgård 5398b7ef6c i2c: xlr: add interrupt support for Sigma Designs chips 
The Sigma Designs variant of this controller has the ability to generate
interrupts.  This is controlled using two additional registers, oddly
enough overlapping with the defined but unused HDSTATIM.

This patch adds support for using this feature instead of busy-looping
if an IRQ is specified.

Signed-off-by: Mans Rullgard <mans@mansr.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2015-12-16 11:42:58 +01:00

471 lines
11 KiB
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/*
* Copyright 2011, Netlogic Microsystems Inc.
* Copyright 2004, Matt Porter <mporter@kernel.crashing.org>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/ioport.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/of_device.h>
#include <linux/clk.h>
#include <linux/interrupt.h>
#include <linux/wait.h>
/* XLR I2C REGISTERS */
#define XLR_I2C_CFG 0x00
#define XLR_I2C_CLKDIV 0x01
#define XLR_I2C_DEVADDR 0x02
#define XLR_I2C_ADDR 0x03
#define XLR_I2C_DATAOUT 0x04
#define XLR_I2C_DATAIN 0x05
#define XLR_I2C_STATUS 0x06
#define XLR_I2C_STARTXFR 0x07
#define XLR_I2C_BYTECNT 0x08
#define XLR_I2C_HDSTATIM 0x09
/* Sigma Designs additional registers */
#define XLR_I2C_INT_EN 0x09
#define XLR_I2C_INT_STAT 0x0a
/* XLR I2C REGISTERS FLAGS */
#define XLR_I2C_BUS_BUSY 0x01
#define XLR_I2C_SDOEMPTY 0x02
#define XLR_I2C_RXRDY 0x04
#define XLR_I2C_ACK_ERR 0x08
#define XLR_I2C_ARB_STARTERR 0x30
/* Register Values */
#define XLR_I2C_CFG_ADDR 0xF8
#define XLR_I2C_CFG_NOADDR 0xFA
#define XLR_I2C_STARTXFR_ND 0x02 /* No Data */
#define XLR_I2C_STARTXFR_RD 0x01 /* Read */
#define XLR_I2C_STARTXFR_WR 0x00 /* Write */
#define XLR_I2C_TIMEOUT 10 /* timeout per byte in msec */
/*
* On XLR/XLS, we need to use __raw_ IO to read the I2C registers
* because they are in the big-endian MMIO area on the SoC.
*
* The readl/writel implementation on XLR/XLS byteswaps, because
* those are for its little-endian PCI space (see arch/mips/Kconfig).
*/
static inline void xlr_i2c_wreg(u32 __iomem *base, unsigned int reg, u32 val)
{
__raw_writel(val, base + reg);
}
static inline u32 xlr_i2c_rdreg(u32 __iomem *base, unsigned int reg)
{
return __raw_readl(base + reg);
}
#define XLR_I2C_FLAG_IRQ 1
struct xlr_i2c_config {
u32 flags; /* optional feature support */
u32 status_busy; /* value of STATUS[0] when busy */
u32 cfg_extra; /* extra CFG bits to set */
};
struct xlr_i2c_private {
struct i2c_adapter adap;
u32 __iomem *iobase;
int irq;
int pos;
struct i2c_msg *msg;
const struct xlr_i2c_config *cfg;
wait_queue_head_t wait;
struct clk *clk;
};
static int xlr_i2c_busy(struct xlr_i2c_private *priv, u32 status)
{
return (status & XLR_I2C_BUS_BUSY) == priv->cfg->status_busy;
}
static int xlr_i2c_idle(struct xlr_i2c_private *priv)
{
return !xlr_i2c_busy(priv, xlr_i2c_rdreg(priv->iobase, XLR_I2C_STATUS));
}
static int xlr_i2c_wait(struct xlr_i2c_private *priv, unsigned long timeout)
{
int status;
int t;
t = wait_event_timeout(priv->wait, xlr_i2c_idle(priv),
msecs_to_jiffies(timeout));
if (!t)
return -ETIMEDOUT;
status = xlr_i2c_rdreg(priv->iobase, XLR_I2C_STATUS);
return status & XLR_I2C_ACK_ERR ? -EIO : 0;
}
static void xlr_i2c_tx_irq(struct xlr_i2c_private *priv, u32 status)
{
struct i2c_msg *msg = priv->msg;
if (status & XLR_I2C_SDOEMPTY)
xlr_i2c_wreg(priv->iobase, XLR_I2C_DATAOUT,
msg->buf[priv->pos++]);
}
static void xlr_i2c_rx_irq(struct xlr_i2c_private *priv, u32 status)
{
struct i2c_msg *msg = priv->msg;
if (status & XLR_I2C_RXRDY)
msg->buf[priv->pos++] =
xlr_i2c_rdreg(priv->iobase, XLR_I2C_DATAIN);
}
static irqreturn_t xlr_i2c_irq(int irq, void *dev_id)
{
struct xlr_i2c_private *priv = dev_id;
struct i2c_msg *msg = priv->msg;
u32 int_stat, status;
int_stat = xlr_i2c_rdreg(priv->iobase, XLR_I2C_INT_STAT);
if (!int_stat)
return IRQ_NONE;
xlr_i2c_wreg(priv->iobase, XLR_I2C_INT_STAT, int_stat);
if (!msg)
return IRQ_HANDLED;
status = xlr_i2c_rdreg(priv->iobase, XLR_I2C_STATUS);
if (priv->pos < msg->len) {
if (msg->flags & I2C_M_RD)
xlr_i2c_rx_irq(priv, status);
else
xlr_i2c_tx_irq(priv, status);
}
if (!xlr_i2c_busy(priv, status))
wake_up(&priv->wait);
return IRQ_HANDLED;
}
static int xlr_i2c_tx(struct xlr_i2c_private *priv, u16 len,
u8 *buf, u16 addr)
{
struct i2c_adapter *adap = &priv->adap;
unsigned long timeout, stoptime, checktime;
u32 i2c_status;
int pos, timedout;
u8 offset;
u32 xfer;
if (!len)
return -EOPNOTSUPP;
offset = buf[0];
xlr_i2c_wreg(priv->iobase, XLR_I2C_ADDR, offset);
xlr_i2c_wreg(priv->iobase, XLR_I2C_DEVADDR, addr);
xlr_i2c_wreg(priv->iobase, XLR_I2C_CFG,
XLR_I2C_CFG_ADDR | priv->cfg->cfg_extra);
timeout = msecs_to_jiffies(XLR_I2C_TIMEOUT);
stoptime = jiffies + timeout;
timedout = 0;
if (len == 1) {
xlr_i2c_wreg(priv->iobase, XLR_I2C_BYTECNT, len - 1);
xfer = XLR_I2C_STARTXFR_ND;
pos = 1;
} else {
xlr_i2c_wreg(priv->iobase, XLR_I2C_BYTECNT, len - 2);
xlr_i2c_wreg(priv->iobase, XLR_I2C_DATAOUT, buf[1]);
xfer = XLR_I2C_STARTXFR_WR;
pos = 2;
}
priv->pos = pos;
retry:
/* retry can only happen on the first byte */
xlr_i2c_wreg(priv->iobase, XLR_I2C_STARTXFR, xfer);
if (priv->irq > 0)
return xlr_i2c_wait(priv, XLR_I2C_TIMEOUT * len);
while (!timedout) {
checktime = jiffies;
i2c_status = xlr_i2c_rdreg(priv->iobase, XLR_I2C_STATUS);
if ((i2c_status & XLR_I2C_SDOEMPTY) && pos < len) {
xlr_i2c_wreg(priv->iobase, XLR_I2C_DATAOUT, buf[pos++]);
/* reset timeout on successful xmit */
stoptime = jiffies + timeout;
}
timedout = time_after(checktime, stoptime);
if (i2c_status & XLR_I2C_ARB_STARTERR) {
if (timedout)
break;
goto retry;
}
if (i2c_status & XLR_I2C_ACK_ERR)
return -EIO;
if (!xlr_i2c_busy(priv, i2c_status) && pos >= len)
return 0;
}
dev_err(&adap->dev, "I2C transmit timeout\n");
return -ETIMEDOUT;
}
static int xlr_i2c_rx(struct xlr_i2c_private *priv, u16 len, u8 *buf, u16 addr)
{
struct i2c_adapter *adap = &priv->adap;
u32 i2c_status;
unsigned long timeout, stoptime, checktime;
int nbytes, timedout;
if (!len)
return -EOPNOTSUPP;
xlr_i2c_wreg(priv->iobase, XLR_I2C_CFG,
XLR_I2C_CFG_NOADDR | priv->cfg->cfg_extra);
xlr_i2c_wreg(priv->iobase, XLR_I2C_BYTECNT, len - 1);
xlr_i2c_wreg(priv->iobase, XLR_I2C_DEVADDR, addr);
priv->pos = 0;
timeout = msecs_to_jiffies(XLR_I2C_TIMEOUT);
stoptime = jiffies + timeout;
timedout = 0;
nbytes = 0;
retry:
xlr_i2c_wreg(priv->iobase, XLR_I2C_STARTXFR, XLR_I2C_STARTXFR_RD);
if (priv->irq > 0)
return xlr_i2c_wait(priv, XLR_I2C_TIMEOUT * len);
while (!timedout) {
checktime = jiffies;
i2c_status = xlr_i2c_rdreg(priv->iobase, XLR_I2C_STATUS);
if (i2c_status & XLR_I2C_RXRDY) {
if (nbytes >= len)
return -EIO; /* should not happen */
buf[nbytes++] =
xlr_i2c_rdreg(priv->iobase, XLR_I2C_DATAIN);
/* reset timeout on successful read */
stoptime = jiffies + timeout;
}
timedout = time_after(checktime, stoptime);
if (i2c_status & XLR_I2C_ARB_STARTERR) {
if (timedout)
break;
goto retry;
}
if (i2c_status & XLR_I2C_ACK_ERR)
return -EIO;
if (!xlr_i2c_busy(priv, i2c_status))
return 0;
}
dev_err(&adap->dev, "I2C receive timeout\n");
return -ETIMEDOUT;
}
static int xlr_i2c_xfer(struct i2c_adapter *adap,
struct i2c_msg *msgs, int num)
{
struct i2c_msg *msg;
int i;
int ret = 0;
struct xlr_i2c_private *priv = i2c_get_adapdata(adap);
ret = clk_enable(priv->clk);
if (ret)
return ret;
if (priv->irq)
xlr_i2c_wreg(priv->iobase, XLR_I2C_INT_EN, 0xf);
for (i = 0; ret == 0 && i < num; i++) {
msg = &msgs[i];
priv->msg = msg;
if (msg->flags & I2C_M_RD)
ret = xlr_i2c_rx(priv, msg->len, &msg->buf[0],
msg->addr);
else
ret = xlr_i2c_tx(priv, msg->len, &msg->buf[0],
msg->addr);
}
if (priv->irq)
xlr_i2c_wreg(priv->iobase, XLR_I2C_INT_EN, 0);
clk_disable(priv->clk);
priv->msg = NULL;
return (ret != 0) ? ret : num;
}
static u32 xlr_func(struct i2c_adapter *adap)
{
/* Emulate SMBUS over I2C */
return (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) | I2C_FUNC_I2C;
}
static struct i2c_algorithm xlr_i2c_algo = {
.master_xfer = xlr_i2c_xfer,
.functionality = xlr_func,
};
static const struct xlr_i2c_config xlr_i2c_config_default = {
.status_busy = XLR_I2C_BUS_BUSY,
.cfg_extra = 0,
};
static const struct xlr_i2c_config xlr_i2c_config_tangox = {
.flags = XLR_I2C_FLAG_IRQ,
.status_busy = 0,
.cfg_extra = 1 << 8,
};
static const struct of_device_id xlr_i2c_dt_ids[] = {
{
.compatible = "sigma,smp8642-i2c",
.data = &xlr_i2c_config_tangox,
},
{ }
};
static int xlr_i2c_probe(struct platform_device *pdev)
{
const struct of_device_id *match;
struct xlr_i2c_private *priv;
struct resource *res;
struct clk *clk;
unsigned long clk_rate;
unsigned long clk_div;
u32 busfreq;
int irq;
int ret;
priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
match = of_match_device(xlr_i2c_dt_ids, &pdev->dev);
if (match)
priv->cfg = match->data;
else
priv->cfg = &xlr_i2c_config_default;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
priv->iobase = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(priv->iobase))
return PTR_ERR(priv->iobase);
irq = platform_get_irq(pdev, 0);
if (irq > 0 && (priv->cfg->flags & XLR_I2C_FLAG_IRQ)) {
priv->irq = irq;
xlr_i2c_wreg(priv->iobase, XLR_I2C_INT_EN, 0);
xlr_i2c_wreg(priv->iobase, XLR_I2C_INT_STAT, 0xf);
ret = devm_request_irq(&pdev->dev, priv->irq, xlr_i2c_irq,
IRQF_SHARED, dev_name(&pdev->dev),
priv);
if (ret)
return ret;
init_waitqueue_head(&priv->wait);
}
if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
&busfreq))
busfreq = 100000;
clk = devm_clk_get(&pdev->dev, NULL);
if (!IS_ERR(clk)) {
ret = clk_prepare_enable(clk);
if (ret)
return ret;
clk_rate = clk_get_rate(clk);
clk_div = DIV_ROUND_UP(clk_rate, 2 * busfreq);
xlr_i2c_wreg(priv->iobase, XLR_I2C_CLKDIV, clk_div);
clk_disable(clk);
priv->clk = clk;
}
priv->adap.dev.parent = &pdev->dev;
priv->adap.dev.of_node = pdev->dev.of_node;
priv->adap.owner = THIS_MODULE;
priv->adap.algo_data = priv;
priv->adap.algo = &xlr_i2c_algo;
priv->adap.nr = pdev->id;
priv->adap.class = I2C_CLASS_HWMON;
snprintf(priv->adap.name, sizeof(priv->adap.name), "xlr-i2c");
i2c_set_adapdata(&priv->adap, priv);
ret = i2c_add_numbered_adapter(&priv->adap);
if (ret < 0) {
dev_err(&priv->adap.dev, "Failed to add i2c bus.\n");
return ret;
}
platform_set_drvdata(pdev, priv);
dev_info(&priv->adap.dev, "Added I2C Bus.\n");
return 0;
}
static int xlr_i2c_remove(struct platform_device *pdev)
{
struct xlr_i2c_private *priv;
priv = platform_get_drvdata(pdev);
i2c_del_adapter(&priv->adap);
clk_unprepare(priv->clk);
return 0;
}
static struct platform_driver xlr_i2c_driver = {
.probe = xlr_i2c_probe,
.remove = xlr_i2c_remove,
.driver = {
.name = "xlr-i2cbus",
.of_match_table = xlr_i2c_dt_ids,
},
};
module_platform_driver(xlr_i2c_driver);
MODULE_AUTHOR("Ganesan Ramalingam <ganesanr@netlogicmicro.com>");
MODULE_DESCRIPTION("XLR/XLS SoC I2C Controller driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:xlr-i2cbus");
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