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i2c: pxa: implement generic i2c bus recovery

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Implement generic GPIO-based I2C bus recovery for the PXA I2C driver.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
This commit is contained in:
Russell King 2020-05-13 10:33:12 +01:00 committed by Wolfram Sang
parent 4f118a7e46
commit 7c9ec2c525
1 changed files with 159 additions and 17 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

176
drivers/i2c/busses/i2c-pxa.c
View file

@ -20,6 +20,7 @@
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/interrupt.h>
@ -28,6 +29,7 @@
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/platform_data/i2c-pxa.h>
#include <linux/slab.h>
@ -260,6 +262,11 @@ struct pxa_i2c {
bool highmode_enter;
u32 fm_mask;
u32 hs_mask;
struct i2c_bus_recovery_info recovery;
struct pinctrl *pinctrl;
struct pinctrl_state *pinctrl_default;
struct pinctrl_state *pinctrl_recovery;
};
#define _IBMR(i2c) ((i2c)->reg_ibmr)
@ -559,13 +566,8 @@ static void i2c_pxa_set_slave(struct pxa_i2c *i2c, int errcode)
#define i2c_pxa_set_slave(i2c, err) do { } while (0)
#endif
static void i2c_pxa_reset(struct pxa_i2c *i2c)
static void i2c_pxa_do_reset(struct pxa_i2c *i2c)
{
pr_debug("Resetting I2C Controller Unit\n");
/* abort any transfer currently under way */
i2c_pxa_abort(i2c);
/* reset according to 9.8 */
writel(ICR_UR, _ICR(i2c));
writel(I2C_ISR_INIT, _ISR(i2c));
@ -584,12 +586,25 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c)
#endif
i2c_pxa_set_slave(i2c, 0);
}
static void i2c_pxa_enable(struct pxa_i2c *i2c)
{
/* enable unit */
writel(readl(_ICR(i2c)) | ICR_IUE, _ICR(i2c));
udelay(100);
}
static void i2c_pxa_reset(struct pxa_i2c *i2c)
{
pr_debug("Resetting I2C Controller Unit\n");
/* abort any transfer currently under way */
i2c_pxa_abort(i2c);
i2c_pxa_do_reset(i2c);
i2c_pxa_enable(i2c);
}
#ifdef CONFIG_I2C_PXA_SLAVE
/*
@ -1043,6 +1058,7 @@ static int i2c_pxa_do_xfer(struct pxa_i2c *i2c, struct i2c_msg *msg, int num)
ret = i2c_pxa_wait_bus_not_busy(i2c);
if (ret) {
dev_err(&i2c->adap.dev, "i2c_pxa: timeout waiting for bus free\n");
i2c_recover_bus(&i2c->adap);
goto out;
}
@ -1088,6 +1104,7 @@ static int i2c_pxa_do_xfer(struct pxa_i2c *i2c, struct i2c_msg *msg, int num)
if (!timeout && i2c->msg_num) {
i2c_pxa_scream_blue_murder(i2c, "timeout with active message");
i2c_recover_bus(&i2c->adap);
ret = I2C_RETRY;
}
@ -1277,6 +1294,129 @@ static int i2c_pxa_probe_pdata(struct platform_device *pdev,
return 0;
}
static void i2c_pxa_prepare_recovery(struct i2c_adapter *adap)
{
struct pxa_i2c *i2c = adap->algo_data;
u32 ibmr = readl(_IBMR(i2c));
/*
* Program the GPIOs to reflect the current I2C bus state while
* we transition to recovery; this avoids glitching the bus.
*/
gpiod_set_value(i2c->recovery.scl_gpiod, ibmr & IBMR_SCLS);
gpiod_set_value(i2c->recovery.sda_gpiod, ibmr & IBMR_SDAS);
WARN_ON(pinctrl_select_state(i2c->pinctrl, i2c->pinctrl_recovery));
}
static void i2c_pxa_unprepare_recovery(struct i2c_adapter *adap)
{
struct pxa_i2c *i2c = adap->algo_data;
u32 isr;
/*
* The bus should now be free. Clear up the I2C controller before
* handing control of the bus back to avoid the bus changing state.
*/
isr = readl(_ISR(i2c));
if (isr & (ISR_UB | ISR_IBB)) {
dev_dbg(&i2c->adap.dev,
"recovery: resetting controller, ISR=0x%08x\n", isr);
i2c_pxa_do_reset(i2c);
}
WARN_ON(pinctrl_select_state(i2c->pinctrl, i2c->pinctrl_default));
dev_dbg(&i2c->adap.dev, "recovery: IBMR 0x%08x ISR 0x%08x\n",
readl(_IBMR(i2c)), readl(_ISR(i2c)));
i2c_pxa_enable(i2c);
}
static int i2c_pxa_init_recovery(struct pxa_i2c *i2c)
{
struct i2c_bus_recovery_info *bri = &i2c->recovery;
struct device *dev = i2c->adap.dev.parent;
/*
* When slave mode is enabled, we are not the only master on the bus.
* Bus recovery can only be performed when we are the master, which
* we can't be certain of. Therefore, when slave mode is enabled, do
* not configure bus recovery.
*/
if (IS_ENABLED(CONFIG_I2C_PXA_SLAVE))
return 0;
i2c->pinctrl = devm_pinctrl_get(dev);
if (IS_ERR(i2c->pinctrl))
return PTR_ERR(i2c->pinctrl);
if (!i2c->pinctrl)
return 0;
i2c->pinctrl_default = pinctrl_lookup_state(i2c->pinctrl,
PINCTRL_STATE_DEFAULT);
i2c->pinctrl_recovery = pinctrl_lookup_state(i2c->pinctrl, "recovery");
if (IS_ERR(i2c->pinctrl_default) || IS_ERR(i2c->pinctrl_recovery)) {
dev_info(dev, "missing pinmux recovery information: %ld %ld\n",
PTR_ERR(i2c->pinctrl_default),
PTR_ERR(i2c->pinctrl_recovery));
return 0;
}
/*
* Claiming GPIOs can influence the pinmux state, and may glitch the
* I2C bus. Do this carefully.
*/
bri->scl_gpiod = devm_gpiod_get(dev, "scl", GPIOD_OUT_HIGH_OPEN_DRAIN);
if (bri->scl_gpiod == ERR_PTR(-EPROBE_DEFER))
return -EPROBE_DEFER;
if (IS_ERR(bri->scl_gpiod)) {
dev_info(dev, "missing scl gpio recovery information: %pe\n",
bri->scl_gpiod);
return 0;
}
/*
* We have SCL. Pull SCL low and wait a bit so that SDA glitches
* have no effect.
*/
gpiod_direction_output(bri->scl_gpiod, 0);
udelay(10);
bri->sda_gpiod = devm_gpiod_get(dev, "sda", GPIOD_OUT_HIGH_OPEN_DRAIN);
/* Wait a bit in case of a SDA glitch, and then release SCL. */
udelay(10);
gpiod_direction_output(bri->scl_gpiod, 1);
if (bri->sda_gpiod == ERR_PTR(-EPROBE_DEFER))
return -EPROBE_DEFER;
if (IS_ERR(bri->sda_gpiod)) {
dev_info(dev, "missing sda gpio recovery information: %pe\n",
bri->sda_gpiod);
return 0;
}
bri->prepare_recovery = i2c_pxa_prepare_recovery;
bri->unprepare_recovery = i2c_pxa_unprepare_recovery;
bri->recover_bus = i2c_generic_scl_recovery;
i2c->adap.bus_recovery_info = bri;
/*
* Claiming GPIOs can change the pinmux state, which confuses the
* pinctrl since pinctrl's idea of the current setting is unaffected
* by the pinmux change caused by claiming the GPIO. Work around that
* by switching pinctrl to the GPIO state here. We do it this way to
* avoid glitching the I2C bus.
*/
pinctrl_select_state(i2c->pinctrl, i2c->pinctrl_recovery);
return pinctrl_select_state(i2c->pinctrl, i2c->pinctrl_default);
}
static int i2c_pxa_probe(struct platform_device *dev)
{
struct i2c_pxa_platform_data *plat = dev_get_platdata(&dev->dev);
@ -1289,6 +1429,16 @@ static int i2c_pxa_probe(struct platform_device *dev)
if (!i2c)
return -ENOMEM;
/* Default adapter num to device id; i2c_pxa_probe_dt can override. */
i2c->adap.nr = dev->id;
i2c->adap.owner = THIS_MODULE;
i2c->adap.retries = 5;
i2c->adap.algo_data = i2c;
i2c->adap.dev.parent = &dev->dev;
#ifdef CONFIG_OF
i2c->adap.dev.of_node = dev->dev.of_node;
#endif
res = platform_get_resource(dev, IORESOURCE_MEM, 0);
i2c->reg_base = devm_ioremap_resource(&dev->dev, res);
if (IS_ERR(i2c->reg_base))
@ -1298,8 +1448,9 @@ static int i2c_pxa_probe(struct platform_device *dev)
if (irq < 0)
return irq;
/* Default adapter num to device id; i2c_pxa_probe_dt can override. */
i2c->adap.nr = dev->id;
ret = i2c_pxa_init_recovery(i2c);
if (ret)
return ret;
ret = i2c_pxa_probe_dt(dev, i2c, &i2c_type);
if (ret > 0)
@ -1307,9 +1458,6 @@ static int i2c_pxa_probe(struct platform_device *dev)
if (ret < 0)
return ret;
i2c->adap.owner = THIS_MODULE;
i2c->adap.retries = 5;
spin_lock_init(&i2c->lock);
init_waitqueue_head(&i2c->wait);
@ -1375,12 +1523,6 @@ static int i2c_pxa_probe(struct platform_device *dev)
i2c_pxa_reset(i2c);
i2c->adap.algo_data = i2c;
i2c->adap.dev.parent = &dev->dev;
#ifdef CONFIG_OF
i2c->adap.dev.of_node = dev->dev.of_node;
#endif
ret = i2c_add_numbered_adapter(&i2c->adap);
if (ret < 0)
goto ereqirq;