[PATCH v3 0/9] i2c: add support for filters

[PATCH v3 0/9] i2c: add support for filters

[Eugen.Hristev]

From: Eugen Hristev <eugen.hristev@microchip.com>

Hello,

This series adds support for analog and digital filters for i2c controllers

This series is based on the series:
[PATCH v2 0/9] i2c: at91: filters support for at91 SoCs
and enhanced to add the bindings for all controllers plus an extra binding
for the width of the spikes in nanoseconds.

First, bindings are created for
'i2c-ana-filter'
'i2c-dig-filter'
'i2c-filter-width-ns'

The support is added in the i2c core to retrieve filter width and add it
to the timings structure.
Next, the at91 driver is enhanced for supporting digital filter, advanced
digital filter (with selectable spike width) and the analog filter.

Finally the device tree for two boards are modified to make use of the
new properties.

This series is the result of the comments on the ML in the direction
requested: to make the bindings globally available for i2c drivers.

Changes in v3:
- made bindings global for i2c controllers and modified accordingly
- gave up PADFCDF bit because it's a lack in datasheet
- the computation on the width of the spike is based on periph clock as it
is done for hold time.

Changes in v2:
- added device tree bindings and support for enable-ana-filt and
enable-dig-filt
- added the new properties to the DT for sama5d4_xplained/sama5d2_xplained

Eugen Hristev (9):
  dt-bindings: i2c: at91: add new compatible
  dt-bindings: i2c: add bindings for i2c analog and digital filter
  i2c: add support for filter-width-ns optional property
  i2c: at91: add new platform support for sam9x60
  i2c: at91: add support for digital filtering
  i2c: at91: add support for advanced digital filtering
  i2c: at91: add support for analog filtering
  ARM: dts: at91: sama5d2_xplained: add analog and digital filter for
    i2c
  ARM: dts: at91: sama5d4_xplained: add analog filter for i2c

 Documentation/devicetree/bindings/i2c/i2c-at91.txt |  3 +-
 Documentation/devicetree/bindings/i2c/i2c.txt      | 11 +++++
 arch/arm/boot/dts/at91-sama5d2_xplained.dts        |  6 +++
 arch/arm/boot/dts/at91-sama5d4_xplained.dts        |  1 +
 drivers/i2c/busses/i2c-at91-core.c                 | 38 +++++++++++++++++
 drivers/i2c/busses/i2c-at91-master.c               | 49 ++++++++++++++++++++--
 drivers/i2c/busses/i2c-at91.h                      | 13 ++++++
 drivers/i2c/i2c-core-base.c                        |  2 +
 include/linux/i2c.h                                |  2 +
 9 files changed, 121 insertions(+), 4 deletions(-)

-- 
2.7.4

[PATCH v3 1/9] dt-bindings: i2c: at91: add new compatible

[Eugen.Hristev]

From: Eugen Hristev <eugen.hristev@microchip.com>

Add compatible for new Microchip SoC, sam9x60

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
 Documentation/devicetree/bindings/i2c/i2c-at91.txt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-at91.txt b/Documentation/devicetree/bindings/i2c/i2c-at91.txt
index b7cec17..2210f43 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-at91.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-at91.txt
@@ -3,7 +3,8 @@ I2C for Atmel platforms
 Required properties :
 - compatible : Must be "atmel,at91rm9200-i2c", "atmel,at91sam9261-i2c",
      "atmel,at91sam9260-i2c", "atmel,at91sam9g20-i2c", "atmel,at91sam9g10-i2c",
-     "atmel,at91sam9x5-i2c", "atmel,sama5d4-i2c" or "atmel,sama5d2-i2c"
+     "atmel,at91sam9x5-i2c", "atmel,sama5d4-i2c", "atmel,sama5d2-i2c" or
+     "microchip,sam9x60-i2c"
 - reg: physical base address of the controller and length of memory mapped
      region.
 - interrupts: interrupt number to the cpu.
-- 
2.7.4

[PATCH v3 2/9] dt-bindings: i2c: add bindings for i2c analog and digital filter

[Eugen.Hristev]

From: Eugen Hristev <eugen.hristev@microchip.com>

Some i2c controllers have a built-in digital or analog filter.
This is specifically required depending on the hardware PCB/board.
Some controllers also allow specifying the maximum width of the
spikes that can be filtered. The width length can be specified in nanoseconds.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
 Documentation/devicetree/bindings/i2c/i2c.txt | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt
index 44efafd..a2d31aa 100644
--- a/Documentation/devicetree/bindings/i2c/i2c.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c.txt
@@ -55,6 +55,17 @@ wants to support one of the below features, it should adapt the bindings below.
 	Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C
 	specification.
 
+- i2c-ana-filter
+	Enable analog filter for i2c lines.
+
+- i2c-dig-filter
+	Enable digital filter for i2c lines.
+
+- i2c-filter-width-ns
+	Width of spikes which can be filtered by either digital or analog
+	filters (i2c-ana-filtr or i2c-dig-filtr). This width is specified
+	in nanoseconds.
+
 - interrupts
 	interrupts used by the device.
 
-- 
2.7.4

[PATCH v3 3/9] i2c: add support for filter-width-ns optional property

[Eugen.Hristev]

From: Eugen Hristev <eugen.hristev@microchip.com>

This optional timing property specifies the width of the spikes on the i2c
lines (in ns) that can be filtered out by built-in analog or digital filters
which are embedded in some i2c controllers.
Include it in the timings structure and read it as integer property.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
 drivers/i2c/i2c-core-base.c | 2 ++
 include/linux/i2c.h         | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 9e43508..73d1c62 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1658,6 +1658,8 @@ void i2c_parse_fw_timings(struct device *dev, struct i2c_timings *t, bool use_de
 		t->sda_fall_ns = t->scl_fall_ns;
 
 	device_property_read_u32(dev, "i2c-sda-hold-time-ns", &t->sda_hold_ns);
+
+	device_property_read_u32(dev, "i2c-filter-width-ns", &t->filter_width_ns);
 }
 EXPORT_SYMBOL_GPL(i2c_parse_fw_timings);
 
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 1308126..dfb6525 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -563,6 +563,7 @@ struct i2c_lock_operations {
  * @scl_int_delay_ns: time IP core additionally needs to setup SCL in ns
  * @sda_fall_ns: time SDA signal takes to fall in ns; t(f) in the I2C specification
  * @sda_hold_ns: time IP core additionally needs to hold SDA in ns
+ * @filter_width_ns: width in ns of spikes on i2c lines that the IP core can filter out
  */
 struct i2c_timings {
 	u32 bus_freq_hz;
@@ -571,6 +572,7 @@ struct i2c_timings {
 	u32 scl_int_delay_ns;
 	u32 sda_fall_ns;
 	u32 sda_hold_ns;
+	u32 filter_width_ns;
 };
 
 /**
-- 
2.7.4

[PATCH v3 4/9] i2c: at91: add new platform support for sam9x60

[Eugen.Hristev]

From: Eugen Hristev <eugen.hristev@microchip.com>

Add new platform data support for the sam9x60 SoC

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
 drivers/i2c/busses/i2c-at91-core.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/i2c/busses/i2c-at91-core.c b/drivers/i2c/busses/i2c-at91-core.c
index 8d55cdd..a663a7a 100644
--- a/drivers/i2c/busses/i2c-at91-core.c
+++ b/drivers/i2c/busses/i2c-at91-core.c
@@ -148,6 +148,14 @@ static struct at91_twi_pdata sama5d2_config = {
 	.has_hold_field = true,
 };
 
+static struct at91_twi_pdata sam9x60_config = {
+	.clk_max_div = 7,
+	.clk_offset = 4,
+	.has_unre_flag = true,
+	.has_alt_cmd = true,
+	.has_hold_field = true,
+};
+
 static const struct of_device_id atmel_twi_dt_ids[] = {
 	{
 		.compatible = "atmel,at91rm9200-i2c",
@@ -174,6 +182,9 @@ static const struct of_device_id atmel_twi_dt_ids[] = {
 		.compatible = "atmel,sama5d2-i2c",
 		.data = &sama5d2_config,
 	}, {
+		.compatible = "microchip,sam9x60-i2c",
+		.data = &sam9x60_config,
+	}, {
 		/* sentinel */
 	}
 };
-- 
2.7.4

[PATCH v3 5/9] i2c: at91: add support for digital filtering

[Eugen.Hristev]

From: Eugen Hristev <eugen.hristev@microchip.com>

Add new platform data support for digital filtering for i2c.
The sama5d4, 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 | 9 +++++++++
 drivers/i2c/busses/i2c-at91.h        | 5 +++++
 3 files changed, 23 insertions(+)

diff --git a/drivers/i2c/busses/i2c-at91-core.c b/drivers/i2c/busses/i2c-at91-core.c
index a663a7a..62610af 100644
--- a/drivers/i2c/busses/i2c-at91-core.c
+++ b/drivers/i2c/busses/i2c-at91-core.c
@@ -68,6 +68,7 @@ static struct at91_twi_pdata at91rm9200_config = {
 	.has_unre_flag = true,
 	.has_alt_cmd = false,
 	.has_hold_field = false,
+	.has_dig_filtr = false,
 };
 
 static struct at91_twi_pdata at91sam9261_config = {
@@ -76,6 +77,7 @@ static struct at91_twi_pdata at91sam9261_config = {
 	.has_unre_flag = false,
 	.has_alt_cmd = false,
 	.has_hold_field = false,
+	.has_dig_filtr = false,
 };
 
 static struct at91_twi_pdata at91sam9260_config = {
@@ -84,6 +86,7 @@ static struct at91_twi_pdata at91sam9260_config = {
 	.has_unre_flag = false,
 	.has_alt_cmd = false,
 	.has_hold_field = false,
+	.has_dig_filtr = false,
 };
 
 static struct at91_twi_pdata at91sam9g20_config = {
@@ -92,6 +95,7 @@ static struct at91_twi_pdata at91sam9g20_config = {
 	.has_unre_flag = false,
 	.has_alt_cmd = false,
 	.has_hold_field = false,
+	.has_dig_filtr = false,
 };
 
 static struct at91_twi_pdata at91sam9g10_config = {
@@ -100,6 +104,7 @@ static struct at91_twi_pdata at91sam9g10_config = {
 	.has_unre_flag = false,
 	.has_alt_cmd = false,
 	.has_hold_field = false,
+	.has_dig_filtr = false,
 };
 
 static const struct platform_device_id at91_twi_devtypes[] = {
@@ -130,6 +135,7 @@ static struct at91_twi_pdata at91sam9x5_config = {
 	.has_unre_flag = false,
 	.has_alt_cmd = false,
 	.has_hold_field = false,
+	.has_dig_filtr = false,
 };
 
 static struct at91_twi_pdata sama5d4_config = {
@@ -138,6 +144,7 @@ static struct at91_twi_pdata sama5d4_config = {
 	.has_unre_flag = false,
 	.has_alt_cmd = false,
 	.has_hold_field = true,
+	.has_dig_filtr = true,
 };
 
 static struct at91_twi_pdata sama5d2_config = {
@@ -146,6 +153,7 @@ static struct at91_twi_pdata sama5d2_config = {
 	.has_unre_flag = true,
 	.has_alt_cmd = true,
 	.has_hold_field = true,
+	.has_dig_filtr = true,
 };
 
 static struct at91_twi_pdata sam9x60_config = {
@@ -154,6 +162,7 @@ static struct at91_twi_pdata sam9x60_config = {
 	.has_unre_flag = true,
 	.has_alt_cmd = true,
 	.has_hold_field = true,
+	.has_dig_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 e87232f..099161a 100644
--- a/drivers/i2c/busses/i2c-at91-master.c
+++ b/drivers/i2c/busses/i2c-at91-master.c
@@ -31,12 +31,18 @@
 
 void at91_init_twi_bus_master(struct at91_twi_dev *dev)
 {
+	struct at91_twi_pdata *pdata = dev->pdata;
+
 	/* FIFO should be enabled immediately after the software reset */
 	if (dev->fifo_size)
 		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_FIFOEN);
 	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSEN);
 	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVDIS);
 	at91_twi_write(dev, AT91_TWI_CWGR, dev->twi_cwgr_reg);
+
+	/* enable digital filter */
+	if (pdata->has_dig_filtr && dev->enable_dig_filt)
+		at91_twi_write(dev, AT91_TWI_FILTR, AT91_TWI_FILTR_FILT);
 }
 
 /*
@@ -792,6 +798,9 @@ int at91_twi_probe_master(struct platform_device *pdev,
 		dev_info(dev->dev, "Using FIFO (%u data)\n", dev->fifo_size);
 	}
 
+	dev->enable_dig_filt = of_property_read_bool(pdev->dev.of_node,
+						     "i2c-dig-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 499b506..c75447e 100644
--- a/drivers/i2c/busses/i2c-at91.h
+++ b/drivers/i2c/busses/i2c-at91.h
@@ -84,6 +84,9 @@
 #define	AT91_TWI_ACR_DATAL(len)	((len) & 0xff)
 #define	AT91_TWI_ACR_DIR	BIT(8)
 
+#define AT91_TWI_FILTR		0x0044
+#define AT91_TWI_FILTR_FILT	BIT(0)
+
 #define	AT91_TWI_FMR		0x0050	/* FIFO Mode Register */
 #define	AT91_TWI_FMR_TXRDYM(mode)	(((mode) & 0x3) << 0)
 #define	AT91_TWI_FMR_TXRDYM_MASK	(0x3 << 0)
@@ -108,6 +111,7 @@ struct at91_twi_pdata {
 	bool has_unre_flag;
 	bool has_alt_cmd;
 	bool has_hold_field;
+	bool has_dig_filtr;
 	struct at_dma_slave dma_slave;
 };
 
@@ -145,6 +149,7 @@ struct at91_twi_dev {
 	unsigned smr;
 	struct i2c_client *slave;
 #endif
+	bool enable_dig_filt;
 };
 
 unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg);
-- 
2.7.4

[PATCH v3 6/9] i2c: at91: add support for advanced digital filtering

[Eugen.Hristev]

From: Eugen Hristev <eugen.hristev@microchip.com>

Add new platform data support for advanced digital filtering for i2c.
The sama5d2 and sam9x60 support this feature.
This digital filter allows the user to configure the maximum
width of the spikes that can be filtered.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
 drivers/i2c/busses/i2c-at91-core.c   |  9 +++++++++
 drivers/i2c/busses/i2c-at91-master.c | 30 +++++++++++++++++++++++++++---
 drivers/i2c/busses/i2c-at91.h        |  5 +++++
 3 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-at91-core.c b/drivers/i2c/busses/i2c-at91-core.c
index 62610af..3bbe37c 100644
--- a/drivers/i2c/busses/i2c-at91-core.c
+++ b/drivers/i2c/busses/i2c-at91-core.c
@@ -69,6 +69,7 @@ static struct at91_twi_pdata at91rm9200_config = {
 	.has_alt_cmd = false,
 	.has_hold_field = false,
 	.has_dig_filtr = false,
+	.has_adv_dig_filtr = false,
 };
 
 static struct at91_twi_pdata at91sam9261_config = {
@@ -78,6 +79,7 @@ static struct at91_twi_pdata at91sam9261_config = {
 	.has_alt_cmd = false,
 	.has_hold_field = false,
 	.has_dig_filtr = false,
+	.has_adv_dig_filtr = false,
 };
 
 static struct at91_twi_pdata at91sam9260_config = {
@@ -87,6 +89,7 @@ static struct at91_twi_pdata at91sam9260_config = {
 	.has_alt_cmd = false,
 	.has_hold_field = false,
 	.has_dig_filtr = false,
+	.has_adv_dig_filtr = false,
 };
 
 static struct at91_twi_pdata at91sam9g20_config = {
@@ -96,6 +99,7 @@ static struct at91_twi_pdata at91sam9g20_config = {
 	.has_alt_cmd = false,
 	.has_hold_field = false,
 	.has_dig_filtr = false,
+	.has_adv_dig_filtr = false,
 };
 
 static struct at91_twi_pdata at91sam9g10_config = {
@@ -105,6 +109,7 @@ static struct at91_twi_pdata at91sam9g10_config = {
 	.has_alt_cmd = false,
 	.has_hold_field = false,
 	.has_dig_filtr = false,
+	.has_adv_dig_filtr = false,
 };
 
 static const struct platform_device_id at91_twi_devtypes[] = {
@@ -136,6 +141,7 @@ static struct at91_twi_pdata at91sam9x5_config = {
 	.has_alt_cmd = false,
 	.has_hold_field = false,
 	.has_dig_filtr = false,
+	.has_adv_dig_filtr = false,
 };
 
 static struct at91_twi_pdata sama5d4_config = {
@@ -145,6 +151,7 @@ static struct at91_twi_pdata sama5d4_config = {
 	.has_alt_cmd = false,
 	.has_hold_field = true,
 	.has_dig_filtr = true,
+	.has_adv_dig_filtr = false,
 };
 
 static struct at91_twi_pdata sama5d2_config = {
@@ -154,6 +161,7 @@ static struct at91_twi_pdata sama5d2_config = {
 	.has_alt_cmd = true,
 	.has_hold_field = true,
 	.has_dig_filtr = true,
+	.has_adv_dig_filtr = true,
 };
 
 static struct at91_twi_pdata sam9x60_config = {
@@ -163,6 +171,7 @@ static struct at91_twi_pdata sam9x60_config = {
 	.has_alt_cmd = true,
 	.has_hold_field = true,
 	.has_dig_filtr = true,
+	.has_adv_dig_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 099161a..344fd26 100644
--- a/drivers/i2c/busses/i2c-at91-master.c
+++ b/drivers/i2c/busses/i2c-at91-master.c
@@ -43,6 +43,12 @@ 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);
+
+	/* 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));
 }
 
 /*
@@ -51,7 +57,7 @@ void at91_init_twi_bus_master(struct at91_twi_dev *dev)
  */
 static void at91_calc_twi_clock(struct at91_twi_dev *dev)
 {
-	int ckdiv, cdiv, div, hold = 0;
+	int ckdiv, cdiv, div, hold = 0, filter_width = 0;
 	struct at91_twi_pdata *pdata = dev->pdata;
 	int offset = pdata->clk_offset;
 	int max_ckdiv = pdata->clk_max_div;
@@ -90,11 +96,29 @@ static void at91_calc_twi_clock(struct at91_twi_dev *dev)
 		}
 	}
 
+	if (pdata->has_adv_dig_filtr) {
+		/*
+		 * filter width = 0 to AT91_TWI_FILTR_THRES_MAX
+		 * peripheral clocks
+		 */
+		filter_width = DIV_ROUND_UP(t->filter_width_ns
+				* (clk_get_rate(dev->clk) / 1000), 1000000);
+		if (filter_width > AT91_TWI_FILTR_THRES_MAX) {
+			dev_warn(dev->dev,
+				"Filter threshold set to its maximum value (%d instead of %d)\n",
+				AT91_TWI_FILTR_THRES_MAX, filter_width);
+			filter_width = AT91_TWI_FILTR_THRES_MAX;
+		}
+	}
+
 	dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv
 			    | AT91_TWI_CWGR_HOLD(hold);
 
-	dev_dbg(dev->dev, "cdiv %d ckdiv %d hold %d (%d ns)\n",
-		cdiv, ckdiv, hold, t->sda_hold_ns);
+	dev->filter_width = filter_width;
+
+	dev_dbg(dev->dev, "cdiv %d ckdiv %d hold %d (%d ns), filter_width %d (%d ns)\n",
+		cdiv, ckdiv, hold, t->sda_hold_ns, filter_width,
+		t->filter_width_ns);
 }
 
 static void at91_twi_dma_cleanup(struct at91_twi_dev *dev)
diff --git a/drivers/i2c/busses/i2c-at91.h b/drivers/i2c/busses/i2c-at91.h
index c75447e..d7cf01e3 100644
--- a/drivers/i2c/busses/i2c-at91.h
+++ b/drivers/i2c/busses/i2c-at91.h
@@ -86,6 +86,9 @@
 
 #define AT91_TWI_FILTR		0x0044
 #define AT91_TWI_FILTR_FILT	BIT(0)
+#define AT91_TWI_FILTR_THRES(v)		((v) << 8)
+#define AT91_TWI_FILTR_THRES_MAX	7
+#define AT91_TWI_FILTR_THRES_MASK	GENMASK(10, 8)
 
 #define	AT91_TWI_FMR		0x0050	/* FIFO Mode Register */
 #define	AT91_TWI_FMR_TXRDYM(mode)	(((mode) & 0x3) << 0)
@@ -112,6 +115,7 @@ struct at91_twi_pdata {
 	bool has_alt_cmd;
 	bool has_hold_field;
 	bool has_dig_filtr;
+	bool has_adv_dig_filtr;
 	struct at_dma_slave dma_slave;
 };
 
@@ -150,6 +154,7 @@ struct at91_twi_dev {
 	struct i2c_client *slave;
 #endif
 	bool enable_dig_filt;
+	u32 filter_width;
 };
 
 unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg);
-- 
2.7.4

[PATCH v3 7/9] i2c: at91: add support for analog filtering

[Eugen.Hristev]

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

[PATCH v3 8/9] ARM: dts: at91: sama5d2_xplained: add analog and digital filter for i2c

[Eugen.Hristev]

From: Eugen Hristev <eugen.hristev@microchip.com>

Add property for analog and digital filter for i2c1 and i2c2 nodes
for sama5d2_xplained

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
 arch/arm/boot/dts/at91-sama5d2_xplained.dts | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm/boot/dts/at91-sama5d2_xplained.dts b/arch/arm/boot/dts/at91-sama5d2_xplained.dts
index 808e399..965326c 100644
--- a/arch/arm/boot/dts/at91-sama5d2_xplained.dts
+++ b/arch/arm/boot/dts/at91-sama5d2_xplained.dts
@@ -334,6 +334,9 @@
 					pinctrl-names = "default";
 					pinctrl-0 = <&pinctrl_flx4_default>;
 					atmel,fifo-size = <16>;
+					i2c-ana-filter;
+					i2c-dig-filter;
+					i2c-filter-width-ns = <35>;
 					status = "okay";
 				};
 			};
@@ -342,6 +345,9 @@
 				dmas = <0>, <0>;
 				pinctrl-names = "default";
 				pinctrl-0 = <&pinctrl_i2c1_default>;
+				i2c-ana-filter;
+				i2c-dig-filter;
+				i2c-filter-width-ns = <35>;
 				status = "okay";
 
 				at24@54 {
-- 
2.7.4

[PATCH v3 9/9] ARM: dts: at91: sama5d4_xplained: add digital filter for i2c

[Eugen.Hristev]

From: Eugen Hristev <eugen.hristev@microchip.com>

Add property for digital filter for i2c0 node sama5d4_xplained

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
 arch/arm/boot/dts/at91-sama5d4_xplained.dts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/boot/dts/at91-sama5d4_xplained.dts b/arch/arm/boot/dts/at91-sama5d4_xplained.dts
index fdfc37d..298113c 100644
--- a/arch/arm/boot/dts/at91-sama5d4_xplained.dts
+++ b/arch/arm/boot/dts/at91-sama5d4_xplained.dts
@@ -49,6 +49,7 @@
 			};
 
 			i2c0: i2c@f8014000 {
+				i2c-dig-filter;
 				status = "okay";
 			};
 
-- 
2.7.4

Re: [PATCH v3 0/9] i2c: add support for filters

[Ludovic Desroches]

On Tue, Jul 09, 2019 at 03:19:26PM +0200, Eugen Hristev - M18282 wrote:
> From: Eugen Hristev <eugen.hristev@microchip.com>
> 
> Hello,
> 
> This series adds support for analog and digital filters for i2c controllers
> 
> This series is based on the series:
> [PATCH v2 0/9] i2c: at91: filters support for at91 SoCs
> and enhanced to add the bindings for all controllers plus an extra binding
> for the width of the spikes in nanoseconds.
> 
> First, bindings are created for
> 'i2c-ana-filter'
> 'i2c-dig-filter'
> 'i2c-filter-width-ns'
> 
> The support is added in the i2c core to retrieve filter width and add it
> to the timings structure.
> Next, the at91 driver is enhanced for supporting digital filter, advanced
> digital filter (with selectable spike width) and the analog filter.
> 
> Finally the device tree for two boards are modified to make use of the
> new properties.
> 
> This series is the result of the comments on the ML in the direction
> requested: to make the bindings globally available for i2c drivers.
> 
> Changes in v3:
> - made bindings global for i2c controllers and modified accordingly
> - gave up PADFCDF bit because it's a lack in datasheet
> - the computation on the width of the spike is based on periph clock as it
> is done for hold time.
> 
> Changes in v2:
> - added device tree bindings and support for enable-ana-filt and
> enable-dig-filt
> - added the new properties to the DT for sama5d4_xplained/sama5d2_xplained
> 
> Eugen Hristev (9):
>   dt-bindings: i2c: at91: add new compatible
>   dt-bindings: i2c: add bindings for i2c analog and digital filter
>   i2c: add support for filter-width-ns optional property
>   i2c: at91: add new platform support for sam9x60
>   i2c: at91: add support for digital filtering
>   i2c: at91: add support for advanced digital filtering
>   i2c: at91: add support for analog filtering
>   ARM: dts: at91: sama5d2_xplained: add analog and digital filter for
>     i2c
>   ARM: dts: at91: sama5d4_xplained: add analog filter for i2c
> 
>  Documentation/devicetree/bindings/i2c/i2c-at91.txt |  3 +-
>  Documentation/devicetree/bindings/i2c/i2c.txt      | 11 +++++
>  arch/arm/boot/dts/at91-sama5d2_xplained.dts        |  6 +++
>  arch/arm/boot/dts/at91-sama5d4_xplained.dts        |  1 +
>  drivers/i2c/busses/i2c-at91-core.c                 | 38 +++++++++++++++++
>  drivers/i2c/busses/i2c-at91-master.c               | 49 ++++++++++++++++++++--
>  drivers/i2c/busses/i2c-at91.h                      | 13 ++++++
>  drivers/i2c/i2c-core-base.c                        |  2 +
>  include/linux/i2c.h                                |  2 +
>  9 files changed, 121 insertions(+), 4 deletions(-)

Hi,

I don't know if it will fit other vendors need concerning the binding
but for Microchip it sounds good.

Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
for the whole serie.

Regards

Ludovic

Re: [PATCH v3 1/9] dt-bindings: i2c: at91: add new compatible

[Rob Herring]

On Tue, 9 Jul 2019 13:19:29 +0000, <Eugen.Hristev@microchip.com> wrote:
> From: Eugen Hristev <eugen.hristev@microchip.com>
> 
> Add compatible for new Microchip SoC, sam9x60
> 
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> ---
>  Documentation/devicetree/bindings/i2c/i2c-at91.txt | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 

Reviewed-by: Rob Herring <robh@kernel.org>

Re: [PATCH v3 2/9] dt-bindings: i2c: add bindings for i2c analog and digital filter

[Rob Herring]

On Tue, 9 Jul 2019 13:19:33 +0000, <Eugen.Hristev@microchip.com> wrote:
> From: Eugen Hristev <eugen.hristev@microchip.com>
> 
> Some i2c controllers have a built-in digital or analog filter.
> This is specifically required depending on the hardware PCB/board.
> Some controllers also allow specifying the maximum width of the
> spikes that can be filtered. The width length can be specified in nanoseconds.
> 
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> ---
>  Documentation/devicetree/bindings/i2c/i2c.txt | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 

Reviewed-by: Rob Herring <robh@kernel.org>

Re: [PATCH v3 0/9] i2c: add support for filters

[Eugen.Hristev]

On 12.07.2019 11:20, Ludovic Desroches wrote:
> On Tue, Jul 09, 2019 at 03:19:26PM +0200, Eugen Hristev - M18282 wrote:
>> From: Eugen Hristev <eugen.hristev@microchip.com>
>>
>> Hello,
>>
>> This series adds support for analog and digital filters for i2c controllers
>>
>> This series is based on the series:
>> [PATCH v2 0/9] i2c: at91: filters support for at91 SoCs
>> and enhanced to add the bindings for all controllers plus an extra binding
>> for the width of the spikes in nanoseconds.
>>
>> First, bindings are created for
>> 'i2c-ana-filter'
>> 'i2c-dig-filter'
>> 'i2c-filter-width-ns'
>>
>> The support is added in the i2c core to retrieve filter width and add it
>> to the timings structure.
>> Next, the at91 driver is enhanced for supporting digital filter, advanced
>> digital filter (with selectable spike width) and the analog filter.
>>
>> Finally the device tree for two boards are modified to make use of the
>> new properties.
>>
>> This series is the result of the comments on the ML in the direction
>> requested: to make the bindings globally available for i2c drivers.
>>
>> Changes in v3:
>> - made bindings global for i2c controllers and modified accordingly
>> - gave up PADFCDF bit because it's a lack in datasheet
>> - the computation on the width of the spike is based on periph clock as it
>> is done for hold time.
>>
>> Changes in v2:
>> - added device tree bindings and support for enable-ana-filt and
>> enable-dig-filt
>> - added the new properties to the DT for sama5d4_xplained/sama5d2_xplained
>>
>> Eugen Hristev (9):
>>    dt-bindings: i2c: at91: add new compatible
>>    dt-bindings: i2c: add bindings for i2c analog and digital filter
>>    i2c: add support for filter-width-ns optional property
>>    i2c: at91: add new platform support for sam9x60
>>    i2c: at91: add support for digital filtering
>>    i2c: at91: add support for advanced digital filtering
>>    i2c: at91: add support for analog filtering
>>    ARM: dts: at91: sama5d2_xplained: add analog and digital filter for
>>      i2c
>>    ARM: dts: at91: sama5d4_xplained: add analog filter for i2c
>>
>>   Documentation/devicetree/bindings/i2c/i2c-at91.txt |  3 +-
>>   Documentation/devicetree/bindings/i2c/i2c.txt      | 11 +++++
>>   arch/arm/boot/dts/at91-sama5d2_xplained.dts        |  6 +++
>>   arch/arm/boot/dts/at91-sama5d4_xplained.dts        |  1 +
>>   drivers/i2c/busses/i2c-at91-core.c                 | 38 +++++++++++++++++
>>   drivers/i2c/busses/i2c-at91-master.c               | 49 ++++++++++++++++++++--
>>   drivers/i2c/busses/i2c-at91.h                      | 13 ++++++
>>   drivers/i2c/i2c-core-base.c                        |  2 +
>>   include/linux/i2c.h                                |  2 +
>>   9 files changed, 121 insertions(+), 4 deletions(-)
> 
> Hi,
> 
> I don't know if it will fit other vendors need concerning the binding
> but for Microchip it sounds good.
> 
> Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
> for the whole serie.
> 
> Regards
> 
> Ludovic
> 

Hello Wolfram,

What is the plan for this patch series?

Thanks,
Eugen

Re: [PATCH v3 0/9] i2c: add support for filters

[Wolfram Sang]

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> > I don't know if it will fit other vendors need concerning the binding
> > but for Microchip it sounds good.
> > 
> > Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
> > for the whole serie.
> > 
> > Regards
> > 
> > Ludovic
> > 
> 
> Hello Wolfram,
> 
> What is the plan for this patch series?

I hope to review it this weekend and my hope it is good to go for 5.4.


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Re: [PATCH v3 2/9] dt-bindings: i2c: add bindings for i2c analog and digital filter

[Wolfram Sang]

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On Tue, Jul 09, 2019 at 01:19:33PM +0000, Eugen.Hristev@microchip.com wrote:
> From: Eugen Hristev <eugen.hristev@microchip.com>
> 
> Some i2c controllers have a built-in digital or analog filter.
> This is specifically required depending on the hardware PCB/board.
> Some controllers also allow specifying the maximum width of the
> spikes that can be filtered. The width length can be specified in nanoseconds.
> 
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> ---
>  Documentation/devicetree/bindings/i2c/i2c.txt | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt
> index 44efafd..a2d31aa 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c.txt
> @@ -55,6 +55,17 @@ wants to support one of the below features, it should adapt the bindings below.
>  	Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C
>  	specification.
>  
> +- i2c-ana-filter
> +	Enable analog filter for i2c lines.
> +
> +- i2c-dig-filter
> +	Enable digital filter for i2c lines.

Would you be OK with writing out 'analog' and 'digital' in full form?
The abrreviation doesn't save us much, I'd think, and I didn't find
similar wording in existing bindings.

> +
> +- i2c-filter-width-ns
> +	Width of spikes which can be filtered by either digital or analog
> +	filters (i2c-ana-filtr or i2c-dig-filtr). This width is specified
> +	in nanoseconds.
> +
>  - interrupts
>  	interrupts used by the device.
>  
> -- 
> 2.7.4
> 

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Re: [PATCH v3 5/9] i2c: at91: add support for digital filtering

[Wolfram Sang]

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> diff --git a/drivers/i2c/busses/i2c-at91-core.c b/drivers/i2c/busses/i2c-at91-core.c
> index a663a7a..62610af 100644
> --- a/drivers/i2c/busses/i2c-at91-core.c
> +++ b/drivers/i2c/busses/i2c-at91-core.c
> @@ -68,6 +68,7 @@ static struct at91_twi_pdata at91rm9200_config = {
>  	.has_unre_flag = true,
>  	.has_alt_cmd = false,
>  	.has_hold_field = false,
> +	.has_dig_filtr = false,

Hmm, 'false' is the default. Maybe not for this series, but it might
make sense to clean up the driver afterwards removing the superfluous
'false'. The precedence will make adding new properties much simpler.


> +	dev->enable_dig_filt = of_property_read_bool(pdev->dev.of_node,
> +						     "i2c-dig-filter");
> +

What do you think of the idea to introduce 'flags' to struct i2c_timings
and parse the bindings in the core, too? Then you'd have sth like:

	if (t->flags & I2C_TIMINGS_ANALOG_FILTER)

Would that be useful for you?


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Re: [PATCH v3 5/9] i2c: at91: add support for digital filtering

[Wolfram Sang]

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> > +	dev->enable_dig_filt = of_property_read_bool(pdev->dev.of_node,
> > +						     "i2c-dig-filter");
> > +
> 
> What do you think of the idea to introduce 'flags' to struct i2c_timings
> and parse the bindings in the core, too? Then you'd have sth like:
> 
> 	if (t->flags & I2C_TIMINGS_ANALOG_FILTER)
> 
> Would that be useful for you?

Forgot to say, we can also implement this incrementally to make sure
your patches land in 5.4 in case you are currently busy with sth else.


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Re: [PATCH v3 0/9] i2c: add support for filters

[Wolfram Sang]

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> > What is the plan for this patch series?
> 
> I hope to review it this weekend and my hope it is good to go for 5.4.

Series looks good basically. Just a few comments for some patches. See
there.

Thanks!


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Re: [PATCH v3 5/9] i2c: at91: add support for digital filtering

[Eugen.Hristev]

On 31.08.2019 15:17, Wolfram Sang wrote:
> 
>>> +	dev->enable_dig_filt = of_property_read_bool(pdev->dev.of_node,
>>> +						     "i2c-dig-filter");
>>> +
>>
>> What do you think of the idea to introduce 'flags' to struct i2c_timings
>> and parse the bindings in the core, too? Then you'd have sth like:
>>
>> 	if (t->flags & I2C_TIMINGS_ANALOG_FILTER)
>>
>> Would that be useful for you?
> 
> Forgot to say, we can also implement this incrementally to make sure
> your patches land in 5.4 in case you are currently busy with sth else.
> 

Hi Wolfram,

Your idea looks good but I would prefer to have it as a separate 
enhancement patch, after this series gets in.
As things are now, this series/patches do just the filtering part. We 
can then move all the optional 'flags' as another change.
So yes, we can do this incrementally.

Thanks !
Eugen

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