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Commit7c9ec2c

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Russell Kingwsakernel
Russell King
authored andcommitted
i2c: pxa: implement generic i2c bus recovery
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>
1 parent4f118a7 commit7c9ec2c

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1 file changed

+159
-17
lines changed

1 file changed

+159
-17
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‎drivers/i2c/busses/i2c-pxa.c‎

Lines changed: 159 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -20,6 +20,7 @@
2020
#include<linux/delay.h>
2121
#include<linux/err.h>
2222
#include<linux/errno.h>
23+
#include<linux/gpio/consumer.h>
2324
#include<linux/i2c.h>
2425
#include<linux/init.h>
2526
#include<linux/interrupt.h>
@@ -28,6 +29,7 @@
2829
#include<linux/module.h>
2930
#include<linux/of.h>
3031
#include<linux/of_device.h>
32+
#include<linux/pinctrl/consumer.h>
3133
#include<linux/platform_device.h>
3234
#include<linux/platform_data/i2c-pxa.h>
3335
#include<linux/slab.h>
@@ -260,6 +262,11 @@ struct pxa_i2c {
260262
boolhighmode_enter;
261263
u32fm_mask;
262264
u32hs_mask;
265+
266+
structi2c_bus_recovery_inforecovery;
267+
structpinctrl*pinctrl;
268+
structpinctrl_state*pinctrl_default;
269+
structpinctrl_state*pinctrl_recovery;
263270
};
264271

265272
#define_IBMR(i2c)((i2c)->reg_ibmr)
@@ -559,13 +566,8 @@ static void i2c_pxa_set_slave(struct pxa_i2c *i2c, int errcode)
559566
#definei2c_pxa_set_slave(i2c,err)do { } while (0)
560567
#endif
561568

562-
staticvoidi2c_pxa_reset(structpxa_i2c*i2c)
569+
staticvoidi2c_pxa_do_reset(structpxa_i2c*i2c)
563570
{
564-
pr_debug("Resetting I2C Controller Unit\n");
565-
566-
/* abort any transfer currently under way */
567-
i2c_pxa_abort(i2c);
568-
569571
/* reset according to 9.8 */
570572
writel(ICR_UR,_ICR(i2c));
571573
writel(I2C_ISR_INIT,_ISR(i2c));
@@ -584,12 +586,25 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c)
584586
#endif
585587

586588
i2c_pxa_set_slave(i2c,0);
589+
}
587590

591+
staticvoidi2c_pxa_enable(structpxa_i2c*i2c)
592+
{
588593
/* enable unit */
589594
writel(readl(_ICR(i2c)) |ICR_IUE,_ICR(i2c));
590595
udelay(100);
591596
}
592597

598+
staticvoidi2c_pxa_reset(structpxa_i2c*i2c)
599+
{
600+
pr_debug("Resetting I2C Controller Unit\n");
601+
602+
/* abort any transfer currently under way */
603+
i2c_pxa_abort(i2c);
604+
i2c_pxa_do_reset(i2c);
605+
i2c_pxa_enable(i2c);
606+
}
607+
593608

594609
#ifdefCONFIG_I2C_PXA_SLAVE
595610
/*
@@ -1043,6 +1058,7 @@ static int i2c_pxa_do_xfer(struct pxa_i2c *i2c, struct i2c_msg *msg, int num)
10431058
ret=i2c_pxa_wait_bus_not_busy(i2c);
10441059
if (ret) {
10451060
dev_err(&i2c->adap.dev,"i2c_pxa: timeout waiting for bus free\n");
1061+
i2c_recover_bus(&i2c->adap);
10461062
gotoout;
10471063
}
10481064

@@ -1088,6 +1104,7 @@ static int i2c_pxa_do_xfer(struct pxa_i2c *i2c, struct i2c_msg *msg, int num)
10881104

10891105
if (!timeout&&i2c->msg_num) {
10901106
i2c_pxa_scream_blue_murder(i2c,"timeout with active message");
1107+
i2c_recover_bus(&i2c->adap);
10911108
ret=I2C_RETRY;
10921109
}
10931110

@@ -1277,6 +1294,129 @@ static int i2c_pxa_probe_pdata(struct platform_device *pdev,
12771294
return0;
12781295
}
12791296

1297+
staticvoidi2c_pxa_prepare_recovery(structi2c_adapter*adap)
1298+
{
1299+
structpxa_i2c*i2c=adap->algo_data;
1300+
u32ibmr=readl(_IBMR(i2c));
1301+
1302+
/*
1303+
* Program the GPIOs to reflect the current I2C bus state while
1304+
* we transition to recovery; this avoids glitching the bus.
1305+
*/
1306+
gpiod_set_value(i2c->recovery.scl_gpiod,ibmr&IBMR_SCLS);
1307+
gpiod_set_value(i2c->recovery.sda_gpiod,ibmr&IBMR_SDAS);
1308+
1309+
WARN_ON(pinctrl_select_state(i2c->pinctrl,i2c->pinctrl_recovery));
1310+
}
1311+
1312+
staticvoidi2c_pxa_unprepare_recovery(structi2c_adapter*adap)
1313+
{
1314+
structpxa_i2c*i2c=adap->algo_data;
1315+
u32isr;
1316+
1317+
/*
1318+
* The bus should now be free. Clear up the I2C controller before
1319+
* handing control of the bus back to avoid the bus changing state.
1320+
*/
1321+
isr=readl(_ISR(i2c));
1322+
if (isr& (ISR_UB |ISR_IBB)) {
1323+
dev_dbg(&i2c->adap.dev,
1324+
"recovery: resetting controller, ISR=0x%08x\n",isr);
1325+
i2c_pxa_do_reset(i2c);
1326+
}
1327+
1328+
WARN_ON(pinctrl_select_state(i2c->pinctrl,i2c->pinctrl_default));
1329+
1330+
dev_dbg(&i2c->adap.dev,"recovery: IBMR 0x%08x ISR 0x%08x\n",
1331+
readl(_IBMR(i2c)),readl(_ISR(i2c)));
1332+
1333+
i2c_pxa_enable(i2c);
1334+
}
1335+
1336+
staticinti2c_pxa_init_recovery(structpxa_i2c*i2c)
1337+
{
1338+
structi2c_bus_recovery_info*bri=&i2c->recovery;
1339+
structdevice*dev=i2c->adap.dev.parent;
1340+
1341+
/*
1342+
* When slave mode is enabled, we are not the only master on the bus.
1343+
* Bus recovery can only be performed when we are the master, which
1344+
* we can't be certain of. Therefore, when slave mode is enabled, do
1345+
* not configure bus recovery.
1346+
*/
1347+
if (IS_ENABLED(CONFIG_I2C_PXA_SLAVE))
1348+
return0;
1349+
1350+
i2c->pinctrl=devm_pinctrl_get(dev);
1351+
if (IS_ERR(i2c->pinctrl))
1352+
returnPTR_ERR(i2c->pinctrl);
1353+
1354+
if (!i2c->pinctrl)
1355+
return0;
1356+
1357+
i2c->pinctrl_default=pinctrl_lookup_state(i2c->pinctrl,
1358+
PINCTRL_STATE_DEFAULT);
1359+
i2c->pinctrl_recovery=pinctrl_lookup_state(i2c->pinctrl,"recovery");
1360+
1361+
if (IS_ERR(i2c->pinctrl_default)||IS_ERR(i2c->pinctrl_recovery)) {
1362+
dev_info(dev,"missing pinmux recovery information: %ld %ld\n",
1363+
PTR_ERR(i2c->pinctrl_default),
1364+
PTR_ERR(i2c->pinctrl_recovery));
1365+
return0;
1366+
}
1367+
1368+
/*
1369+
* Claiming GPIOs can influence the pinmux state, and may glitch the
1370+
* I2C bus. Do this carefully.
1371+
*/
1372+
bri->scl_gpiod=devm_gpiod_get(dev,"scl",GPIOD_OUT_HIGH_OPEN_DRAIN);
1373+
if (bri->scl_gpiod==ERR_PTR(-EPROBE_DEFER))
1374+
return-EPROBE_DEFER;
1375+
if (IS_ERR(bri->scl_gpiod)) {
1376+
dev_info(dev,"missing scl gpio recovery information: %pe\n",
1377+
bri->scl_gpiod);
1378+
return0;
1379+
}
1380+
1381+
/*
1382+
* We have SCL. Pull SCL low and wait a bit so that SDA glitches
1383+
* have no effect.
1384+
*/
1385+
gpiod_direction_output(bri->scl_gpiod,0);
1386+
udelay(10);
1387+
bri->sda_gpiod=devm_gpiod_get(dev,"sda",GPIOD_OUT_HIGH_OPEN_DRAIN);
1388+
1389+
/* Wait a bit in case of a SDA glitch, and then release SCL. */
1390+
udelay(10);
1391+
gpiod_direction_output(bri->scl_gpiod,1);
1392+
1393+
if (bri->sda_gpiod==ERR_PTR(-EPROBE_DEFER))
1394+
return-EPROBE_DEFER;
1395+
1396+
if (IS_ERR(bri->sda_gpiod)) {
1397+
dev_info(dev,"missing sda gpio recovery information: %pe\n",
1398+
bri->sda_gpiod);
1399+
return0;
1400+
}
1401+
1402+
bri->prepare_recovery=i2c_pxa_prepare_recovery;
1403+
bri->unprepare_recovery=i2c_pxa_unprepare_recovery;
1404+
bri->recover_bus=i2c_generic_scl_recovery;
1405+
1406+
i2c->adap.bus_recovery_info=bri;
1407+
1408+
/*
1409+
* Claiming GPIOs can change the pinmux state, which confuses the
1410+
* pinctrl since pinctrl's idea of the current setting is unaffected
1411+
* by the pinmux change caused by claiming the GPIO. Work around that
1412+
* by switching pinctrl to the GPIO state here. We do it this way to
1413+
* avoid glitching the I2C bus.
1414+
*/
1415+
pinctrl_select_state(i2c->pinctrl,i2c->pinctrl_recovery);
1416+
1417+
returnpinctrl_select_state(i2c->pinctrl,i2c->pinctrl_default);
1418+
}
1419+
12801420
staticinti2c_pxa_probe(structplatform_device*dev)
12811421
{
12821422
structi2c_pxa_platform_data*plat=dev_get_platdata(&dev->dev);
@@ -1289,6 +1429,16 @@ static int i2c_pxa_probe(struct platform_device *dev)
12891429
if (!i2c)
12901430
return-ENOMEM;
12911431

1432+
/* Default adapter num to device id; i2c_pxa_probe_dt can override. */
1433+
i2c->adap.nr=dev->id;
1434+
i2c->adap.owner=THIS_MODULE;
1435+
i2c->adap.retries=5;
1436+
i2c->adap.algo_data=i2c;
1437+
i2c->adap.dev.parent=&dev->dev;
1438+
#ifdefCONFIG_OF
1439+
i2c->adap.dev.of_node=dev->dev.of_node;
1440+
#endif
1441+
12921442
res=platform_get_resource(dev,IORESOURCE_MEM,0);
12931443
i2c->reg_base=devm_ioremap_resource(&dev->dev,res);
12941444
if (IS_ERR(i2c->reg_base))
@@ -1298,18 +1448,16 @@ static int i2c_pxa_probe(struct platform_device *dev)
12981448
if (irq<0)
12991449
returnirq;
13001450

1301-
/* Default adapter num to device id; i2c_pxa_probe_dt can override. */
1302-
i2c->adap.nr=dev->id;
1451+
ret=i2c_pxa_init_recovery(i2c);
1452+
if (ret)
1453+
returnret;
13031454

13041455
ret=i2c_pxa_probe_dt(dev,i2c,&i2c_type);
13051456
if (ret>0)
13061457
ret=i2c_pxa_probe_pdata(dev,i2c,&i2c_type);
13071458
if (ret<0)
13081459
returnret;
13091460

1310-
i2c->adap.owner=THIS_MODULE;
1311-
i2c->adap.retries=5;
1312-
13131461
spin_lock_init(&i2c->lock);
13141462
init_waitqueue_head(&i2c->wait);
13151463

@@ -1375,12 +1523,6 @@ static int i2c_pxa_probe(struct platform_device *dev)
13751523

13761524
i2c_pxa_reset(i2c);
13771525

1378-
i2c->adap.algo_data=i2c;
1379-
i2c->adap.dev.parent=&dev->dev;
1380-
#ifdefCONFIG_OF
1381-
i2c->adap.dev.of_node=dev->dev.of_node;
1382-
#endif
1383-
13841526
ret=i2c_add_numbered_adapter(&i2c->adap);
13851527
if (ret<0)
13861528
gotoereqirq;

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