520 lines
13 KiB
C
520 lines
13 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* BCM2835 master mode driver
|
|
*/
|
|
|
|
#include <linux/clk.h>
|
|
#include <linux/clkdev.h>
|
|
#include <linux/clk-provider.h>
|
|
#include <linux/completion.h>
|
|
#include <linux/err.h>
|
|
#include <linux/i2c.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/io.h>
|
|
#include <linux/module.h>
|
|
#include <linux/of_device.h>
|
|
#include <linux/platform_device.h>
|
|
#include <linux/slab.h>
|
|
|
|
#define BCM2835_I2C_C 0x0
|
|
#define BCM2835_I2C_S 0x4
|
|
#define BCM2835_I2C_DLEN 0x8
|
|
#define BCM2835_I2C_A 0xc
|
|
#define BCM2835_I2C_FIFO 0x10
|
|
#define BCM2835_I2C_DIV 0x14
|
|
#define BCM2835_I2C_DEL 0x18
|
|
#define BCM2835_I2C_CLKT 0x1c
|
|
|
|
#define BCM2835_I2C_C_READ BIT(0)
|
|
#define BCM2835_I2C_C_CLEAR BIT(4) /* bits 4 and 5 both clear */
|
|
#define BCM2835_I2C_C_ST BIT(7)
|
|
#define BCM2835_I2C_C_INTD BIT(8)
|
|
#define BCM2835_I2C_C_INTT BIT(9)
|
|
#define BCM2835_I2C_C_INTR BIT(10)
|
|
#define BCM2835_I2C_C_I2CEN BIT(15)
|
|
|
|
#define BCM2835_I2C_S_TA BIT(0)
|
|
#define BCM2835_I2C_S_DONE BIT(1)
|
|
#define BCM2835_I2C_S_TXW BIT(2)
|
|
#define BCM2835_I2C_S_RXR BIT(3)
|
|
#define BCM2835_I2C_S_TXD BIT(4)
|
|
#define BCM2835_I2C_S_RXD BIT(5)
|
|
#define BCM2835_I2C_S_TXE BIT(6)
|
|
#define BCM2835_I2C_S_RXF BIT(7)
|
|
#define BCM2835_I2C_S_ERR BIT(8)
|
|
#define BCM2835_I2C_S_CLKT BIT(9)
|
|
#define BCM2835_I2C_S_LEN BIT(10) /* Fake bit for SW error reporting */
|
|
|
|
#define BCM2835_I2C_FEDL_SHIFT 16
|
|
#define BCM2835_I2C_REDL_SHIFT 0
|
|
|
|
#define BCM2835_I2C_CDIV_MIN 0x0002
|
|
#define BCM2835_I2C_CDIV_MAX 0xFFFE
|
|
|
|
struct bcm2835_i2c_dev {
|
|
struct device *dev;
|
|
void __iomem *regs;
|
|
int irq;
|
|
struct i2c_adapter adapter;
|
|
struct completion completion;
|
|
struct i2c_msg *curr_msg;
|
|
struct clk *bus_clk;
|
|
int num_msgs;
|
|
u32 msg_err;
|
|
u8 *msg_buf;
|
|
size_t msg_buf_remaining;
|
|
};
|
|
|
|
static inline void bcm2835_i2c_writel(struct bcm2835_i2c_dev *i2c_dev,
|
|
u32 reg, u32 val)
|
|
{
|
|
writel(val, i2c_dev->regs + reg);
|
|
}
|
|
|
|
static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg)
|
|
{
|
|
return readl(i2c_dev->regs + reg);
|
|
}
|
|
|
|
#define to_clk_bcm2835_i2c(_hw) container_of(_hw, struct clk_bcm2835_i2c, hw)
|
|
struct clk_bcm2835_i2c {
|
|
struct clk_hw hw;
|
|
struct bcm2835_i2c_dev *i2c_dev;
|
|
};
|
|
|
|
static int clk_bcm2835_i2c_calc_divider(unsigned long rate,
|
|
unsigned long parent_rate)
|
|
{
|
|
u32 divider = DIV_ROUND_UP(parent_rate, rate);
|
|
|
|
/*
|
|
* Per the datasheet, the register is always interpreted as an even
|
|
* number, by rounding down. In other words, the LSB is ignored. So,
|
|
* if the LSB is set, increment the divider to avoid any issue.
|
|
*/
|
|
if (divider & 1)
|
|
divider++;
|
|
if ((divider < BCM2835_I2C_CDIV_MIN) ||
|
|
(divider > BCM2835_I2C_CDIV_MAX))
|
|
return -EINVAL;
|
|
|
|
return divider;
|
|
}
|
|
|
|
static int clk_bcm2835_i2c_set_rate(struct clk_hw *hw, unsigned long rate,
|
|
unsigned long parent_rate)
|
|
{
|
|
struct clk_bcm2835_i2c *div = to_clk_bcm2835_i2c(hw);
|
|
u32 redl, fedl;
|
|
u32 divider = clk_bcm2835_i2c_calc_divider(rate, parent_rate);
|
|
|
|
if (divider == -EINVAL)
|
|
return -EINVAL;
|
|
|
|
bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_DIV, divider);
|
|
|
|
/*
|
|
* Number of core clocks to wait after falling edge before
|
|
* outputting the next data bit. Note that both FEDL and REDL
|
|
* can't be greater than CDIV/2.
|
|
*/
|
|
fedl = max(divider / 16, 1u);
|
|
|
|
/*
|
|
* Number of core clocks to wait after rising edge before
|
|
* sampling the next incoming data bit.
|
|
*/
|
|
redl = max(divider / 4, 1u);
|
|
|
|
bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_DEL,
|
|
(fedl << BCM2835_I2C_FEDL_SHIFT) |
|
|
(redl << BCM2835_I2C_REDL_SHIFT));
|
|
return 0;
|
|
}
|
|
|
|
static long clk_bcm2835_i2c_round_rate(struct clk_hw *hw, unsigned long rate,
|
|
unsigned long *parent_rate)
|
|
{
|
|
u32 divider = clk_bcm2835_i2c_calc_divider(rate, *parent_rate);
|
|
|
|
return DIV_ROUND_UP(*parent_rate, divider);
|
|
}
|
|
|
|
static unsigned long clk_bcm2835_i2c_recalc_rate(struct clk_hw *hw,
|
|
unsigned long parent_rate)
|
|
{
|
|
struct clk_bcm2835_i2c *div = to_clk_bcm2835_i2c(hw);
|
|
u32 divider = bcm2835_i2c_readl(div->i2c_dev, BCM2835_I2C_DIV);
|
|
|
|
return DIV_ROUND_UP(parent_rate, divider);
|
|
}
|
|
|
|
static const struct clk_ops clk_bcm2835_i2c_ops = {
|
|
.set_rate = clk_bcm2835_i2c_set_rate,
|
|
.round_rate = clk_bcm2835_i2c_round_rate,
|
|
.recalc_rate = clk_bcm2835_i2c_recalc_rate,
|
|
};
|
|
|
|
static struct clk *bcm2835_i2c_register_div(struct device *dev,
|
|
struct clk *mclk,
|
|
struct bcm2835_i2c_dev *i2c_dev)
|
|
{
|
|
struct clk_init_data init;
|
|
struct clk_bcm2835_i2c *priv;
|
|
char name[32];
|
|
const char *mclk_name;
|
|
|
|
snprintf(name, sizeof(name), "%s_div", dev_name(dev));
|
|
|
|
mclk_name = __clk_get_name(mclk);
|
|
|
|
init.ops = &clk_bcm2835_i2c_ops;
|
|
init.name = name;
|
|
init.parent_names = (const char* []) { mclk_name };
|
|
init.num_parents = 1;
|
|
init.flags = 0;
|
|
|
|
priv = devm_kzalloc(dev, sizeof(struct clk_bcm2835_i2c), GFP_KERNEL);
|
|
if (priv == NULL)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
priv->hw.init = &init;
|
|
priv->i2c_dev = i2c_dev;
|
|
|
|
clk_hw_register_clkdev(&priv->hw, "div", dev_name(dev));
|
|
return devm_clk_register(dev, &priv->hw);
|
|
}
|
|
|
|
static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev)
|
|
{
|
|
u32 val;
|
|
|
|
while (i2c_dev->msg_buf_remaining) {
|
|
val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
|
|
if (!(val & BCM2835_I2C_S_TXD))
|
|
break;
|
|
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_FIFO,
|
|
*i2c_dev->msg_buf);
|
|
i2c_dev->msg_buf++;
|
|
i2c_dev->msg_buf_remaining--;
|
|
}
|
|
}
|
|
|
|
static void bcm2835_drain_rxfifo(struct bcm2835_i2c_dev *i2c_dev)
|
|
{
|
|
u32 val;
|
|
|
|
while (i2c_dev->msg_buf_remaining) {
|
|
val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
|
|
if (!(val & BCM2835_I2C_S_RXD))
|
|
break;
|
|
*i2c_dev->msg_buf = bcm2835_i2c_readl(i2c_dev,
|
|
BCM2835_I2C_FIFO);
|
|
i2c_dev->msg_buf++;
|
|
i2c_dev->msg_buf_remaining--;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Repeated Start Condition (Sr)
|
|
* The BCM2835 ARM Peripherals datasheet mentions a way to trigger a Sr when it
|
|
* talks about reading from a slave with 10 bit address. This is achieved by
|
|
* issuing a write, poll the I2CS.TA flag and wait for it to be set, and then
|
|
* issue a read.
|
|
* A comment in https://github.com/raspberrypi/linux/issues/254 shows how the
|
|
* firmware actually does it using polling and says that it's a workaround for
|
|
* a problem in the state machine.
|
|
* It turns out that it is possible to use the TXW interrupt to know when the
|
|
* transfer is active, provided the FIFO has not been prefilled.
|
|
*/
|
|
|
|
static void bcm2835_i2c_start_transfer(struct bcm2835_i2c_dev *i2c_dev)
|
|
{
|
|
u32 c = BCM2835_I2C_C_ST | BCM2835_I2C_C_I2CEN;
|
|
struct i2c_msg *msg = i2c_dev->curr_msg;
|
|
bool last_msg = (i2c_dev->num_msgs == 1);
|
|
|
|
if (!i2c_dev->num_msgs)
|
|
return;
|
|
|
|
i2c_dev->num_msgs--;
|
|
i2c_dev->msg_buf = msg->buf;
|
|
i2c_dev->msg_buf_remaining = msg->len;
|
|
|
|
if (msg->flags & I2C_M_RD)
|
|
c |= BCM2835_I2C_C_READ | BCM2835_I2C_C_INTR;
|
|
else
|
|
c |= BCM2835_I2C_C_INTT;
|
|
|
|
if (last_msg)
|
|
c |= BCM2835_I2C_C_INTD;
|
|
|
|
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_A, msg->addr);
|
|
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DLEN, msg->len);
|
|
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, c);
|
|
}
|
|
|
|
static void bcm2835_i2c_finish_transfer(struct bcm2835_i2c_dev *i2c_dev)
|
|
{
|
|
i2c_dev->curr_msg = NULL;
|
|
i2c_dev->num_msgs = 0;
|
|
|
|
i2c_dev->msg_buf = NULL;
|
|
i2c_dev->msg_buf_remaining = 0;
|
|
}
|
|
|
|
/*
|
|
* Note about I2C_C_CLEAR on error:
|
|
* The I2C_C_CLEAR on errors will take some time to resolve -- if you were in
|
|
* non-idle state and I2C_C_READ, it sets an abort_rx flag and runs through
|
|
* the state machine to send a NACK and a STOP. Since we're setting CLEAR
|
|
* without I2CEN, that NACK will be hanging around queued up for next time
|
|
* we start the engine.
|
|
*/
|
|
|
|
static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data)
|
|
{
|
|
struct bcm2835_i2c_dev *i2c_dev = data;
|
|
u32 val, err;
|
|
|
|
val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
|
|
|
|
err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR);
|
|
if (err) {
|
|
i2c_dev->msg_err = err;
|
|
goto complete;
|
|
}
|
|
|
|
if (val & BCM2835_I2C_S_DONE) {
|
|
if (!i2c_dev->curr_msg) {
|
|
dev_err(i2c_dev->dev, "Got unexpected interrupt (from firmware?)\n");
|
|
} else if (i2c_dev->curr_msg->flags & I2C_M_RD) {
|
|
bcm2835_drain_rxfifo(i2c_dev);
|
|
val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
|
|
}
|
|
|
|
if ((val & BCM2835_I2C_S_RXD) || i2c_dev->msg_buf_remaining)
|
|
i2c_dev->msg_err = BCM2835_I2C_S_LEN;
|
|
else
|
|
i2c_dev->msg_err = 0;
|
|
goto complete;
|
|
}
|
|
|
|
if (val & BCM2835_I2C_S_TXW) {
|
|
if (!i2c_dev->msg_buf_remaining) {
|
|
i2c_dev->msg_err = val | BCM2835_I2C_S_LEN;
|
|
goto complete;
|
|
}
|
|
|
|
bcm2835_fill_txfifo(i2c_dev);
|
|
|
|
if (i2c_dev->num_msgs && !i2c_dev->msg_buf_remaining) {
|
|
i2c_dev->curr_msg++;
|
|
bcm2835_i2c_start_transfer(i2c_dev);
|
|
}
|
|
|
|
return IRQ_HANDLED;
|
|
}
|
|
|
|
if (val & BCM2835_I2C_S_RXR) {
|
|
if (!i2c_dev->msg_buf_remaining) {
|
|
i2c_dev->msg_err = val | BCM2835_I2C_S_LEN;
|
|
goto complete;
|
|
}
|
|
|
|
bcm2835_drain_rxfifo(i2c_dev);
|
|
return IRQ_HANDLED;
|
|
}
|
|
|
|
return IRQ_NONE;
|
|
|
|
complete:
|
|
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR);
|
|
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, BCM2835_I2C_S_CLKT |
|
|
BCM2835_I2C_S_ERR | BCM2835_I2C_S_DONE);
|
|
complete(&i2c_dev->completion);
|
|
|
|
return IRQ_HANDLED;
|
|
}
|
|
|
|
static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
|
|
int num)
|
|
{
|
|
struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
|
|
unsigned long time_left;
|
|
int i;
|
|
|
|
for (i = 0; i < (num - 1); i++)
|
|
if (msgs[i].flags & I2C_M_RD) {
|
|
dev_warn_once(i2c_dev->dev,
|
|
"only one read message supported, has to be last\n");
|
|
return -EOPNOTSUPP;
|
|
}
|
|
|
|
i2c_dev->curr_msg = msgs;
|
|
i2c_dev->num_msgs = num;
|
|
reinit_completion(&i2c_dev->completion);
|
|
|
|
bcm2835_i2c_start_transfer(i2c_dev);
|
|
|
|
time_left = wait_for_completion_timeout(&i2c_dev->completion,
|
|
adap->timeout);
|
|
|
|
bcm2835_i2c_finish_transfer(i2c_dev);
|
|
|
|
if (!time_left) {
|
|
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C,
|
|
BCM2835_I2C_C_CLEAR);
|
|
dev_err(i2c_dev->dev, "i2c transfer timed out\n");
|
|
return -ETIMEDOUT;
|
|
}
|
|
|
|
if (!i2c_dev->msg_err)
|
|
return num;
|
|
|
|
dev_dbg(i2c_dev->dev, "i2c transfer failed: %x\n", i2c_dev->msg_err);
|
|
|
|
if (i2c_dev->msg_err & BCM2835_I2C_S_ERR)
|
|
return -EREMOTEIO;
|
|
|
|
return -EIO;
|
|
}
|
|
|
|
static u32 bcm2835_i2c_func(struct i2c_adapter *adap)
|
|
{
|
|
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
|
|
}
|
|
|
|
static const struct i2c_algorithm bcm2835_i2c_algo = {
|
|
.master_xfer = bcm2835_i2c_xfer,
|
|
.functionality = bcm2835_i2c_func,
|
|
};
|
|
|
|
/*
|
|
* The BCM2835 was reported to have problems with clock stretching:
|
|
* https://www.advamation.com/knowhow/raspberrypi/rpi-i2c-bug.html
|
|
* https://www.raspberrypi.org/forums/viewtopic.php?p=146272
|
|
*/
|
|
static const struct i2c_adapter_quirks bcm2835_i2c_quirks = {
|
|
.flags = I2C_AQ_NO_CLK_STRETCH,
|
|
};
|
|
|
|
static int bcm2835_i2c_probe(struct platform_device *pdev)
|
|
{
|
|
struct bcm2835_i2c_dev *i2c_dev;
|
|
struct resource *mem;
|
|
int ret;
|
|
struct i2c_adapter *adap;
|
|
struct clk *mclk;
|
|
u32 bus_clk_rate;
|
|
|
|
i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
|
|
if (!i2c_dev)
|
|
return -ENOMEM;
|
|
platform_set_drvdata(pdev, i2c_dev);
|
|
i2c_dev->dev = &pdev->dev;
|
|
init_completion(&i2c_dev->completion);
|
|
|
|
mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
|
|
i2c_dev->regs = devm_ioremap_resource(&pdev->dev, mem);
|
|
if (IS_ERR(i2c_dev->regs))
|
|
return PTR_ERR(i2c_dev->regs);
|
|
|
|
mclk = devm_clk_get(&pdev->dev, NULL);
|
|
if (IS_ERR(mclk))
|
|
return dev_err_probe(&pdev->dev, PTR_ERR(mclk),
|
|
"Could not get clock\n");
|
|
|
|
i2c_dev->bus_clk = bcm2835_i2c_register_div(&pdev->dev, mclk, i2c_dev);
|
|
|
|
if (IS_ERR(i2c_dev->bus_clk)) {
|
|
dev_err(&pdev->dev, "Could not register clock\n");
|
|
return PTR_ERR(i2c_dev->bus_clk);
|
|
}
|
|
|
|
ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
|
|
&bus_clk_rate);
|
|
if (ret < 0) {
|
|
dev_warn(&pdev->dev,
|
|
"Could not read clock-frequency property\n");
|
|
bus_clk_rate = I2C_MAX_STANDARD_MODE_FREQ;
|
|
}
|
|
|
|
ret = clk_set_rate_exclusive(i2c_dev->bus_clk, bus_clk_rate);
|
|
if (ret < 0) {
|
|
dev_err(&pdev->dev, "Could not set clock frequency\n");
|
|
return ret;
|
|
}
|
|
|
|
ret = clk_prepare_enable(i2c_dev->bus_clk);
|
|
if (ret) {
|
|
dev_err(&pdev->dev, "Couldn't prepare clock");
|
|
return ret;
|
|
}
|
|
|
|
i2c_dev->irq = platform_get_irq(pdev, 0);
|
|
if (i2c_dev->irq < 0)
|
|
return i2c_dev->irq;
|
|
|
|
ret = request_irq(i2c_dev->irq, bcm2835_i2c_isr, IRQF_SHARED,
|
|
dev_name(&pdev->dev), i2c_dev);
|
|
if (ret) {
|
|
dev_err(&pdev->dev, "Could not request IRQ\n");
|
|
return -ENODEV;
|
|
}
|
|
|
|
adap = &i2c_dev->adapter;
|
|
i2c_set_adapdata(adap, i2c_dev);
|
|
adap->owner = THIS_MODULE;
|
|
adap->class = I2C_CLASS_DEPRECATED;
|
|
snprintf(adap->name, sizeof(adap->name), "bcm2835 (%s)",
|
|
of_node_full_name(pdev->dev.of_node));
|
|
adap->algo = &bcm2835_i2c_algo;
|
|
adap->dev.parent = &pdev->dev;
|
|
adap->dev.of_node = pdev->dev.of_node;
|
|
adap->quirks = of_device_get_match_data(&pdev->dev);
|
|
|
|
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0);
|
|
|
|
ret = i2c_add_adapter(adap);
|
|
if (ret)
|
|
free_irq(i2c_dev->irq, i2c_dev);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int bcm2835_i2c_remove(struct platform_device *pdev)
|
|
{
|
|
struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
|
|
|
|
clk_rate_exclusive_put(i2c_dev->bus_clk);
|
|
clk_disable_unprepare(i2c_dev->bus_clk);
|
|
|
|
free_irq(i2c_dev->irq, i2c_dev);
|
|
i2c_del_adapter(&i2c_dev->adapter);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct of_device_id bcm2835_i2c_of_match[] = {
|
|
{ .compatible = "brcm,bcm2711-i2c" },
|
|
{ .compatible = "brcm,bcm2835-i2c", .data = &bcm2835_i2c_quirks },
|
|
{},
|
|
};
|
|
MODULE_DEVICE_TABLE(of, bcm2835_i2c_of_match);
|
|
|
|
static struct platform_driver bcm2835_i2c_driver = {
|
|
.probe = bcm2835_i2c_probe,
|
|
.remove = bcm2835_i2c_remove,
|
|
.driver = {
|
|
.name = "i2c-bcm2835",
|
|
.of_match_table = bcm2835_i2c_of_match,
|
|
},
|
|
};
|
|
module_platform_driver(bcm2835_i2c_driver);
|
|
|
|
MODULE_AUTHOR("Stephen Warren <swarren@wwwdotorg.org>");
|
|
MODULE_DESCRIPTION("BCM2835 I2C bus adapter");
|
|
MODULE_LICENSE("GPL v2");
|
|
MODULE_ALIAS("platform:i2c-bcm2835");
|