- 根目录:
- drivers
- i2c
- busses
- i2c-efm32.c
/*
* Copyright (C) 2014 Uwe Kleine-Koenig for Pengutronix
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License version 2 as published by the
* Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/i2c.h>
#include <linux/io.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/clk.h>
#define DRIVER_NAME "efm32-i2c"
#define MASK_VAL(mask, val) ((val << __ffs(mask)) & mask)
#define REG_CTRL 0x00
#define REG_CTRL_EN 0x00001
#define REG_CTRL_SLAVE 0x00002
#define REG_CTRL_AUTOACK 0x00004
#define REG_CTRL_AUTOSE 0x00008
#define REG_CTRL_AUTOSN 0x00010
#define REG_CTRL_ARBDIS 0x00020
#define REG_CTRL_GCAMEN 0x00040
#define REG_CTRL_CLHR__MASK 0x00300
#define REG_CTRL_BITO__MASK 0x03000
#define REG_CTRL_BITO_OFF 0x00000
#define REG_CTRL_BITO_40PCC 0x01000
#define REG_CTRL_BITO_80PCC 0x02000
#define REG_CTRL_BITO_160PCC 0x03000
#define REG_CTRL_GIBITO 0x08000
#define REG_CTRL_CLTO__MASK 0x70000
#define REG_CTRL_CLTO_OFF 0x00000
#define REG_CMD 0x04
#define REG_CMD_START 0x00001
#define REG_CMD_STOP 0x00002
#define REG_CMD_ACK 0x00004
#define REG_CMD_NACK 0x00008
#define REG_CMD_CONT 0x00010
#define REG_CMD_ABORT 0x00020
#define REG_CMD_CLEARTX 0x00040
#define REG_CMD_CLEARPC 0x00080
#define REG_STATE 0x08
#define REG_STATE_BUSY 0x00001
#define REG_STATE_MASTER 0x00002
#define REG_STATE_TRANSMITTER 0x00004
#define REG_STATE_NACKED 0x00008
#define REG_STATE_BUSHOLD 0x00010
#define REG_STATE_STATE__MASK 0x000e0
#define REG_STATE_STATE_IDLE 0x00000
#define REG_STATE_STATE_WAIT 0x00020
#define REG_STATE_STATE_START 0x00040
#define REG_STATE_STATE_ADDR 0x00060
#define REG_STATE_STATE_ADDRACK 0x00080
#define REG_STATE_STATE_DATA 0x000a0
#define REG_STATE_STATE_DATAACK 0x000c0
#define REG_STATUS 0x0c
#define REG_STATUS_PSTART 0x00001
#define REG_STATUS_PSTOP 0x00002
#define REG_STATUS_PACK 0x00004
#define REG_STATUS_PNACK 0x00008
#define REG_STATUS_PCONT 0x00010
#define REG_STATUS_PABORT 0x00020
#define REG_STATUS_TXC 0x00040
#define REG_STATUS_TXBL 0x00080
#define REG_STATUS_RXDATAV 0x00100
#define REG_CLKDIV 0x10
#define REG_CLKDIV_DIV__MASK 0x001ff
#define REG_CLKDIV_DIV(div) MASK_VAL(REG_CLKDIV_DIV__MASK, (div))
#define REG_SADDR 0x14
#define REG_SADDRMASK 0x18
#define REG_RXDATA 0x1c
#define REG_RXDATAP 0x20
#define REG_TXDATA 0x24
#define REG_IF 0x28
#define REG_IF_START 0x00001
#define REG_IF_RSTART 0x00002
#define REG_IF_ADDR 0x00004
#define REG_IF_TXC 0x00008
#define REG_IF_TXBL 0x00010
#define REG_IF_RXDATAV 0x00020
#define REG_IF_ACK 0x00040
#define REG_IF_NACK 0x00080
#define REG_IF_MSTOP 0x00100
#define REG_IF_ARBLOST 0x00200
#define REG_IF_BUSERR 0x00400
#define REG_IF_BUSHOLD 0x00800
#define REG_IF_TXOF 0x01000
#define REG_IF_RXUF 0x02000
#define REG_IF_BITO 0x04000
#define REG_IF_CLTO 0x08000
#define REG_IF_SSTOP 0x10000
#define REG_IFS 0x2c
#define REG_IFC 0x30
#define REG_IFC__MASK 0x1ffcf
#define REG_IEN 0x34
#define REG_ROUTE 0x38
#define REG_ROUTE_SDAPEN 0x00001
#define REG_ROUTE_SCLPEN 0x00002
#define REG_ROUTE_LOCATION__MASK 0x00700
#define REG_ROUTE_LOCATION(n) MASK_VAL(REG_ROUTE_LOCATION__MASK, (n))
struct efm32_i2c_ddata {
struct i2c_adapter adapter;
struct clk *clk;
void __iomem *base;
unsigned int irq;
u8 location;
unsigned long frequency;
/* transfer data */
struct completion done;
struct i2c_msg *msgs;
size_t num_msgs;
size_t current_word, current_msg;
int retval;
};
static u32 efm32_i2c_read32(struct efm32_i2c_ddata *ddata, unsigned offset)
{
return readl(ddata->base + offset);
}
static void efm32_i2c_write32(struct efm32_i2c_ddata *ddata,
unsigned offset, u32 value)
{
writel(value, ddata->base + offset);
}
static void efm32_i2c_send_next_msg(struct efm32_i2c_ddata *ddata)
{
struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
efm32_i2c_write32(ddata, REG_CMD, REG_CMD_START);
efm32_i2c_write32(ddata, REG_TXDATA, cur_msg->addr << 1 |
(cur_msg->flags & I2C_M_RD ? 1 : 0));
}
static void efm32_i2c_send_next_byte(struct efm32_i2c_ddata *ddata)
{
struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
if (ddata->current_word >= cur_msg->len) {
/* cur_msg completely transferred */
ddata->current_word = 0;
ddata->current_msg += 1;
if (ddata->current_msg >= ddata->num_msgs) {
efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
complete(&ddata->done);
} else {
efm32_i2c_send_next_msg(ddata);
}
} else {
efm32_i2c_write32(ddata, REG_TXDATA,
cur_msg->buf[ddata->current_word++]);
}
}
static void efm32_i2c_recv_next_byte(struct efm32_i2c_ddata *ddata)
{
struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
cur_msg->buf[ddata->current_word] = efm32_i2c_read32(ddata, REG_RXDATA);
ddata->current_word += 1;
if (ddata->current_word >= cur_msg->len) {
/* cur_msg completely transferred */
ddata->current_word = 0;
ddata->current_msg += 1;
efm32_i2c_write32(ddata, REG_CMD, REG_CMD_NACK);
if (ddata->current_msg >= ddata->num_msgs) {
efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
complete(&ddata->done);
} else {
efm32_i2c_send_next_msg(ddata);
}
} else {
efm32_i2c_write32(ddata, REG_CMD, REG_CMD_ACK);
}
}
static irqreturn_t efm32_i2c_irq(int irq, void *dev_id)
{
struct efm32_i2c_ddata *ddata = dev_id;
struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
u32 irqflag = efm32_i2c_read32(ddata, REG_IF);
u32 state = efm32_i2c_read32(ddata, REG_STATE);
efm32_i2c_write32(ddata, REG_IFC, irqflag & REG_IFC__MASK);
switch (state & REG_STATE_STATE__MASK) {
case REG_STATE_STATE_IDLE:
/* arbitration lost? */
ddata->retval = -EAGAIN;
complete(&ddata->done);
break;
case REG_STATE_STATE_WAIT:
/*
* huh, this shouldn't happen.
* Reset hardware state and get out
*/
ddata->retval = -EIO;
efm32_i2c_write32(ddata, REG_CMD,
REG_CMD_STOP | REG_CMD_ABORT |
REG_CMD_CLEARTX | REG_CMD_CLEARPC);
complete(&ddata->done);
break;
case REG_STATE_STATE_START:
/* "caller" is expected to send an address */
break;
case REG_STATE_STATE_ADDR:
/* wait for Ack or NAck of slave */
break;
case REG_STATE_STATE_ADDRACK:
if (state & REG_STATE_NACKED) {
efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
ddata->retval = -ENXIO;
complete(&ddata->done);
} else if (cur_msg->flags & I2C_M_RD) {
/* wait for slave to send first data byte */
} else {
efm32_i2c_send_next_byte(ddata);
}
break;
case REG_STATE_STATE_DATA:
if (cur_msg->flags & I2C_M_RD) {
efm32_i2c_recv_next_byte(ddata);
} else {
/* wait for Ack or Nack of slave */
}
break;
case REG_STATE_STATE_DATAACK:
if (state & REG_STATE_NACKED) {
efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
complete(&ddata->done);
} else {
efm32_i2c_send_next_byte(ddata);
}
}
return IRQ_HANDLED;
}
static int efm32_i2c_master_xfer(struct i2c_adapter *adap,
struct i2c_msg *msgs, int num)
{
struct efm32_i2c_ddata *ddata = i2c_get_adapdata(adap);
int ret;
if (ddata->msgs)
return -EBUSY;
ddata->msgs = msgs;
ddata->num_msgs = num;
ddata->current_word = 0;
ddata->current_msg = 0;
ddata->retval = -EIO;
reinit_completion(&ddata->done);
dev_dbg(&ddata->adapter.dev, "state: %08x, status: %08x\n",
efm32_i2c_read32(ddata, REG_STATE),
efm32_i2c_read32(ddata, REG_STATUS));
efm32_i2c_send_next_msg(ddata);
wait_for_completion(&ddata->done);
if (ddata->current_msg >= ddata->num_msgs)
ret = ddata->num_msgs;
else
ret = ddata->retval;
return ret;
}
static u32 efm32_i2c_functionality(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static const struct i2c_algorithm efm32_i2c_algo = {
.master_xfer = efm32_i2c_master_xfer,
.functionality = efm32_i2c_functionality,
};
static u32 efm32_i2c_get_configured_location(struct efm32_i2c_ddata *ddata)
{
u32 reg = efm32_i2c_read32(ddata, REG_ROUTE);
return (reg & REG_ROUTE_LOCATION__MASK) >>
__ffs(REG_ROUTE_LOCATION__MASK);
}
static int efm32_i2c_probe(struct platform_device *pdev)
{
struct efm32_i2c_ddata *ddata;
struct resource *res;
unsigned long rate;
struct device_node *np = pdev->dev.of_node;
u32 location, frequency;
int ret;
u32 clkdiv;
if (!np)
return -EINVAL;
ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
if (!ddata)
return -ENOMEM;
platform_set_drvdata(pdev, ddata);
init_completion(&ddata->done);
strlcpy(ddata->adapter.name, pdev->name, sizeof(ddata->adapter.name));
ddata->adapter.owner = THIS_MODULE;
ddata->adapter.algo = &efm32_i2c_algo;
ddata->adapter.dev.parent = &pdev->dev;
ddata->adapter.dev.of_node = pdev->dev.of_node;
i2c_set_adapdata(&ddata->adapter, ddata);
ddata->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(ddata->clk)) {
ret = PTR_ERR(ddata->clk);
dev_err(&pdev->dev, "failed to get clock: %d\n", ret);
return ret;
}
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
dev_err(&pdev->dev, "failed to determine base address\n");
return -ENODEV;
}
if (resource_size(res) < 0x42) {
dev_err(&pdev->dev, "memory resource too small\n");
return -EINVAL;
}
ddata->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(ddata->base))
return PTR_ERR(ddata->base);
ret = platform_get_irq(pdev, 0);
if (ret <= 0) {
dev_err(&pdev->dev, "failed to get irq (%d)\n", ret);
if (!ret)
ret = -EINVAL;
return ret;
}
ddata->irq = ret;
ret = clk_prepare_enable(ddata->clk);
if (ret < 0) {
dev_err(&pdev->dev, "failed to enable clock (%d)\n", ret);
return ret;
}
ret = of_property_read_u32(np, "energymicro,location", &location);
if (ret)
/* fall back to wrongly namespaced property */
ret = of_property_read_u32(np, "efm32,location", &location);
if (!ret) {
dev_dbg(&pdev->dev, "using location %u\n", location);
} else {
/* default to location configured in hardware */
location = efm32_i2c_get_configured_location(ddata);
dev_info(&pdev->dev, "fall back to location %u\n", location);
}
ddata->location = location;
ret = of_property_read_u32(np, "clock-frequency", &frequency);
if (!ret) {
dev_dbg(&pdev->dev, "using frequency %u\n", frequency);
} else {
frequency = 100000;
dev_info(&pdev->dev, "defaulting to 100 kHz\n");
}
ddata->frequency = frequency;
rate = clk_get_rate(ddata->clk);
if (!rate) {
dev_err(&pdev->dev, "there is no input clock available\n");
ret = -EINVAL;
goto err_disable_clk;
}
clkdiv = DIV_ROUND_UP(rate, 8 * ddata->frequency) - 1;
if (clkdiv >= 0x200) {
dev_err(&pdev->dev,
"input clock too fast (%lu) to divide down to bus freq (%lu)",
rate, ddata->frequency);
ret = -EINVAL;
goto err_disable_clk;
}
dev_dbg(&pdev->dev, "input clock = %lu, bus freq = %lu, clkdiv = %lu\n",
rate, ddata->frequency, (unsigned long)clkdiv);
efm32_i2c_write32(ddata, REG_CLKDIV, REG_CLKDIV_DIV(clkdiv));
efm32_i2c_write32(ddata, REG_ROUTE, REG_ROUTE_SDAPEN |
REG_ROUTE_SCLPEN |
REG_ROUTE_LOCATION(ddata->location));
efm32_i2c_write32(ddata, REG_CTRL, REG_CTRL_EN |
REG_CTRL_BITO_160PCC | 0 * REG_CTRL_GIBITO);
efm32_i2c_write32(ddata, REG_IFC, REG_IFC__MASK);
efm32_i2c_write32(ddata, REG_IEN, REG_IF_TXC | REG_IF_ACK | REG_IF_NACK
| REG_IF_ARBLOST | REG_IF_BUSERR | REG_IF_RXDATAV);
/* to make bus idle */
efm32_i2c_write32(ddata, REG_CMD, REG_CMD_ABORT);
ret = request_irq(ddata->irq, efm32_i2c_irq, 0, DRIVER_NAME, ddata);
if (ret < 0) {
dev_err(&pdev->dev, "failed to request irq (%d)\n", ret);
return ret;
}
ret = i2c_add_adapter(&ddata->adapter);
if (ret) {
dev_err(&pdev->dev, "failed to add i2c adapter (%d)\n", ret);
free_irq(ddata->irq, ddata);
err_disable_clk:
clk_disable_unprepare(ddata->clk);
}
return ret;
}
static int efm32_i2c_remove(struct platform_device *pdev)
{
struct efm32_i2c_ddata *ddata = platform_get_drvdata(pdev);
i2c_del_adapter(&ddata->adapter);
free_irq(ddata->irq, ddata);
clk_disable_unprepare(ddata->clk);
return 0;
}
static const struct of_device_id efm32_i2c_dt_ids[] = {
{
.compatible = "energymicro,efm32-i2c",
}, {
/* sentinel */
}
};
MODULE_DEVICE_TABLE(of, efm32_i2c_dt_ids);
static struct platform_driver efm32_i2c_driver = {
.probe = efm32_i2c_probe,
.remove = efm32_i2c_remove,
.driver = {
.name = DRIVER_NAME,
.of_match_table = efm32_i2c_dt_ids,
},
};
module_platform_driver(efm32_i2c_driver);
MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>");
MODULE_DESCRIPTION("EFM32 i2c driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" DRIVER_NAME);