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Subject[PATCH v3 7/9] i2c: at91: add support for analog filtering
Date
From: Eugen Hristev <eugen.hristev@microchip.com>

Add support for analog filtering for i2c lines.
The sama5d2 and sam9x60 support this feature.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
drivers/i2c/busses/i2c-at91-core.c | 9 +++++++++
drivers/i2c/busses/i2c-at91-master.c | 18 ++++++++++++++----
drivers/i2c/busses/i2c-at91.h | 3 +++
3 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-at91-core.c b/drivers/i2c/busses/i2c-at91-core.c
index 3bbe37c..d2840ba 100644
--- a/drivers/i2c/busses/i2c-at91-core.c
+++ b/drivers/i2c/busses/i2c-at91-core.c
@@ -70,6 +70,7 @@ static struct at91_twi_pdata at91rm9200_config = {
.has_hold_field = false,
.has_dig_filtr = false,
.has_adv_dig_filtr = false,
+ .has_ana_filtr = false,
};

static struct at91_twi_pdata at91sam9261_config = {
@@ -80,6 +81,7 @@ static struct at91_twi_pdata at91sam9261_config = {
.has_hold_field = false,
.has_dig_filtr = false,
.has_adv_dig_filtr = false,
+ .has_ana_filtr = false,
};

static struct at91_twi_pdata at91sam9260_config = {
@@ -90,6 +92,7 @@ static struct at91_twi_pdata at91sam9260_config = {
.has_hold_field = false,
.has_dig_filtr = false,
.has_adv_dig_filtr = false,
+ .has_ana_filtr = false,
};

static struct at91_twi_pdata at91sam9g20_config = {
@@ -100,6 +103,7 @@ static struct at91_twi_pdata at91sam9g20_config = {
.has_hold_field = false,
.has_dig_filtr = false,
.has_adv_dig_filtr = false,
+ .has_ana_filtr = false,
};

static struct at91_twi_pdata at91sam9g10_config = {
@@ -110,6 +114,7 @@ static struct at91_twi_pdata at91sam9g10_config = {
.has_hold_field = false,
.has_dig_filtr = false,
.has_adv_dig_filtr = false,
+ .has_ana_filtr = false,
};

static const struct platform_device_id at91_twi_devtypes[] = {
@@ -142,6 +147,7 @@ static struct at91_twi_pdata at91sam9x5_config = {
.has_hold_field = false,
.has_dig_filtr = false,
.has_adv_dig_filtr = false,
+ .has_ana_filtr = false,
};

static struct at91_twi_pdata sama5d4_config = {
@@ -152,6 +158,7 @@ static struct at91_twi_pdata sama5d4_config = {
.has_hold_field = true,
.has_dig_filtr = true,
.has_adv_dig_filtr = false,
+ .has_ana_filtr = false,
};

static struct at91_twi_pdata sama5d2_config = {
@@ -162,6 +169,7 @@ static struct at91_twi_pdata sama5d2_config = {
.has_hold_field = true,
.has_dig_filtr = true,
.has_adv_dig_filtr = true,
+ .has_ana_filtr = true,
};

static struct at91_twi_pdata sam9x60_config = {
@@ -172,6 +180,7 @@ static struct at91_twi_pdata sam9x60_config = {
.has_hold_field = true,
.has_dig_filtr = true,
.has_adv_dig_filtr = true,
+ .has_ana_filtr = true,
};

static const struct of_device_id atmel_twi_dt_ids[] = {
diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-at91-master.c
index 344fd26..4b89610 100644
--- a/drivers/i2c/busses/i2c-at91-master.c
+++ b/drivers/i2c/busses/i2c-at91-master.c
@@ -32,6 +32,7 @@
void at91_init_twi_bus_master(struct at91_twi_dev *dev)
{
struct at91_twi_pdata *pdata = dev->pdata;
+ u32 filtr = 0;

/* FIFO should be enabled immediately after the software reset */
if (dev->fifo_size)
@@ -42,13 +43,20 @@ void at91_init_twi_bus_master(struct at91_twi_dev *dev)

/* enable digital filter */
if (pdata->has_dig_filtr && dev->enable_dig_filt)
- at91_twi_write(dev, AT91_TWI_FILTR, AT91_TWI_FILTR_FILT);
+ filtr |= AT91_TWI_FILTR_FILT;

/* enable advanced digital filter */
if (pdata->has_adv_dig_filtr && dev->enable_dig_filt)
- at91_twi_write(dev, AT91_TWI_FILTR, AT91_TWI_FILTR_FILT |
- (AT91_TWI_FILTR_THRES(dev->filter_width) &
- AT91_TWI_FILTR_THRES_MASK));
+ filtr |= AT91_TWI_FILTR_FILT |
+ (AT91_TWI_FILTR_THRES(dev->filter_width) &
+ AT91_TWI_FILTR_THRES_MASK);
+
+ /* enable analog filter */
+ if (pdata->has_ana_filtr && dev->enable_ana_filt)
+ filtr |= AT91_TWI_FILTR_PADFEN;
+
+ if (filtr)
+ at91_twi_write(dev, AT91_TWI_FILTR, filtr);
}

/*
@@ -825,6 +833,8 @@ int at91_twi_probe_master(struct platform_device *pdev,
dev->enable_dig_filt = of_property_read_bool(pdev->dev.of_node,
"i2c-dig-filter");

+ dev->enable_ana_filt = of_property_read_bool(pdev->dev.of_node,
+ "i2c-ana-filter");
at91_calc_twi_clock(dev);

dev->adapter.algo = &at91_twi_algorithm;
diff --git a/drivers/i2c/busses/i2c-at91.h b/drivers/i2c/busses/i2c-at91.h
index d7cf01e3..977a67b 100644
--- a/drivers/i2c/busses/i2c-at91.h
+++ b/drivers/i2c/busses/i2c-at91.h
@@ -86,6 +86,7 @@

#define AT91_TWI_FILTR 0x0044
#define AT91_TWI_FILTR_FILT BIT(0)
+#define AT91_TWI_FILTR_PADFEN BIT(1)
#define AT91_TWI_FILTR_THRES(v) ((v) << 8)
#define AT91_TWI_FILTR_THRES_MAX 7
#define AT91_TWI_FILTR_THRES_MASK GENMASK(10, 8)
@@ -116,6 +117,7 @@ struct at91_twi_pdata {
bool has_hold_field;
bool has_dig_filtr;
bool has_adv_dig_filtr;
+ bool has_ana_filtr;
struct at_dma_slave dma_slave;
};

@@ -154,6 +156,7 @@ struct at91_twi_dev {
struct i2c_client *slave;
#endif
bool enable_dig_filt;
+ bool enable_ana_filt;
u32 filter_width;
};

--
2.7.4
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