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[PATCH v5 0/5] Devicetree support for misc/eeprom/eeprom_93xx46.

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  [PATCH v5 0/5] Devicetree support for misc/eeprom/eeprom_93xx46. Cory Tusar <cory.tusar@pid1solutions.com> - 2016-01-07 05:00 +0100
    [PATCH v5 4/5] misc: eeprom_93xx46: Add quirks to support Atmel AT93C46D device. Cory Tusar <cory.tusar@pid1solutions.com> - 2016-01-07 05:00 +0100

#1303273 — [PATCH v5 0/5] Devicetree support for misc/eeprom/eeprom_93xx46.

This series of patches adds an initial set of devicetree bindings to the
eeprom_93xx46 driver which mirror the configuration options previously
available as a platform device.  These bindings are then extended to
include support for specific Atmel devices in this family and also to
support GPIO-based selection of the device (e.g. for use with an SPI bus
mux).

Additionally, an address aliasing issue with 16-bit read and write
accesses in the eeprom_93xx46 driver discovered during testing is fixed.

Changes since v4:
  - Only forward-declare 'struct gpio_desc' in eeprom_93xx46.h.
  - Reviewed-by: Vladimir Zapolskiy <vz@mleia.com>

Changes since v3:
  - Tested-by: Chris Healy <chris.healy@zii.aero>
    ...on a separate i.MX51 platform with Microchip 93LC46A EEPROM.

Changes since v2:
  - Changed node name to 'eeprom' in DT bindings example.
  - Simplified several bits of return logic.
  - Removed #ifdef CONFIG_OF.
  - Allow compiler to handle promotion to bool return values.
  - Reworked GPIO handling to use gpiod_* functions throughout (and
    fixed an oversight where GPIO flags were being ignored).

Changes since v1:
  - Consolidated all Documentation/devictree additions into a single patch.
  - Clarified compatible string shall be only one of the supported values.
  - Renamed the 'select-gpio' binding to 'select-gpios'.

Cory Tusar (5):
  misc: eeprom_93xx46: Fix 16-bit read and write accesses.
  Documentation: devicetree: Add DT bindings to eeprom_93xx46 driver.
  misc: eeprom_93xx46: Implement eeprom_93xx46 DT bindings.
  misc: eeprom_93xx46: Add quirks to support Atmel AT93C46D device.
  misc: eeprom_93xx46: Add support for a GPIO 'select' line.

 .../devicetree/bindings/misc/eeprom-93xx46.txt     |  25 +++
 drivers/misc/eeprom/eeprom_93xx46.c                | 212 +++++++++++++++++----
 include/linux/eeprom_93xx46.h                      |   9 +
 3 files changed, 210 insertions(+), 36 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/misc/eeprom-93xx46.txt

-- 
2.4.10

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#1303275 — [PATCH v5 4/5] misc: eeprom_93xx46: Add quirks to support Atmel AT93C46D device.

Atmel devices in this family have some quirks not found in other similar
chips - they do not support a sequential read of the entire EEPROM
contents, and the control word sent at the start of each operation
varies in bit length.

This commit adds quirk support to the driver and modifies the read
implementation to support non-sequential reads for consistency with
other misc/eeprom drivers.

Tested on a custom Freescale VF610-based platform, with an AT93C46D
device attached via dspi2.  The spi-gpio driver was used to allow the
necessary non-byte-sized transfers.

Signed-off-by: Cory Tusar <cory.tusar@pid1solutions.com>
Tested-by: Chris Healy <chris.healy@zii.aero>
Reviewed-by: Vladimir Zapolskiy <vz@mleia.com>
---
 drivers/misc/eeprom/eeprom_93xx46.c | 126 ++++++++++++++++++++++++++----------
 include/linux/eeprom_93xx46.h       |   6 ++
 2 files changed, 97 insertions(+), 35 deletions(-)

diff --git a/drivers/misc/eeprom/eeprom_93xx46.c b/drivers/misc/eeprom/eeprom_93xx46.c
index cc27e11..d50bc17 100644
--- a/drivers/misc/eeprom/eeprom_93xx46.c
+++ b/drivers/misc/eeprom/eeprom_93xx46.c
@@ -27,6 +27,15 @@
 #define ADDR_ERAL	0x20
 #define ADDR_EWEN	0x30
 
+struct eeprom_93xx46_devtype_data {
+	unsigned int quirks;
+};
+
+static const struct eeprom_93xx46_devtype_data atmel_at93c46d_data = {
+	.quirks = EEPROM_93XX46_QUIRK_SINGLE_WORD_READ |
+		  EEPROM_93XX46_QUIRK_INSTRUCTION_LENGTH,
+};
+
 struct eeprom_93xx46_dev {
 	struct spi_device *spi;
 	struct eeprom_93xx46_platform_data *pdata;
@@ -35,6 +44,16 @@ struct eeprom_93xx46_dev {
 	int addrlen;
 };
 
+static inline bool has_quirk_single_word_read(struct eeprom_93xx46_dev *edev)
+{
+	return edev->pdata->quirks & EEPROM_93XX46_QUIRK_SINGLE_WORD_READ;
+}
+
+static inline bool has_quirk_instruction_length(struct eeprom_93xx46_dev *edev)
+{
+	return edev->pdata->quirks & EEPROM_93XX46_QUIRK_INSTRUCTION_LENGTH;
+}
+
 static ssize_t
 eeprom_93xx46_bin_read(struct file *filp, struct kobject *kobj,
 		       struct bin_attribute *bin_attr,
@@ -42,58 +61,73 @@ eeprom_93xx46_bin_read(struct file *filp, struct kobject *kobj,
 {
 	struct eeprom_93xx46_dev *edev;
 	struct device *dev;
-	struct spi_message m;
-	struct spi_transfer t[2];
-	int bits, ret;
-	u16 cmd_addr;
+	ssize_t ret = 0;
 
 	dev = container_of(kobj, struct device, kobj);
 	edev = dev_get_drvdata(dev);
 
-	cmd_addr = OP_READ << edev->addrlen;
+	mutex_lock(&edev->lock);
 
-	if (edev->addrlen == 7) {
-		cmd_addr |= off & 0x7f;
-		bits = 10;
-	} else {
-		cmd_addr |= (off >> 1) & 0x3f;
-		bits = 9;
-	}
+	if (edev->pdata->prepare)
+		edev->pdata->prepare(edev);
 
-	dev_dbg(&edev->spi->dev, "read cmd 0x%x, %d Hz\n",
-		cmd_addr, edev->spi->max_speed_hz);
+	while (count) {
+		struct spi_message m;
+		struct spi_transfer t[2] = { { 0 } };
+		u16 cmd_addr = OP_READ << edev->addrlen;
+		size_t nbytes = count;
+		int bits;
+		int err;
+
+		if (edev->addrlen == 7) {
+			cmd_addr |= off & 0x7f;
+			bits = 10;
+			if (has_quirk_single_word_read(edev))
+				nbytes = 1;
+		} else {
+			cmd_addr |= (off >> 1) & 0x3f;
+			bits = 9;
+			if (has_quirk_single_word_read(edev))
+				nbytes = 2;
+		}
 
-	spi_message_init(&m);
-	memset(t, 0, sizeof(t));
+		dev_dbg(&edev->spi->dev, "read cmd 0x%x, %d Hz\n",
+			cmd_addr, edev->spi->max_speed_hz);
 
-	t[0].tx_buf = (char *)&cmd_addr;
-	t[0].len = 2;
-	t[0].bits_per_word = bits;
-	spi_message_add_tail(&t[0], &m);
+		spi_message_init(&m);
 
-	t[1].rx_buf = buf;
-	t[1].len = count;
-	t[1].bits_per_word = 8;
-	spi_message_add_tail(&t[1], &m);
+		t[0].tx_buf = (char *)&cmd_addr;
+		t[0].len = 2;
+		t[0].bits_per_word = bits;
+		spi_message_add_tail(&t[0], &m);
 
-	mutex_lock(&edev->lock);
+		t[1].rx_buf = buf;
+		t[1].len = count;
+		t[1].bits_per_word = 8;
+		spi_message_add_tail(&t[1], &m);
 
-	if (edev->pdata->prepare)
-		edev->pdata->prepare(edev);
+		err = spi_sync(edev->spi, &m);
+		/* have to wait at least Tcsl ns */
+		ndelay(250);
 
-	ret = spi_sync(edev->spi, &m);
-	/* have to wait at least Tcsl ns */
-	ndelay(250);
-	if (ret) {
-		dev_err(&edev->spi->dev, "read %zu bytes at %d: err. %d\n",
-			count, (int)off, ret);
+		if (err) {
+			dev_err(&edev->spi->dev, "read %zu bytes at %d: err. %d\n",
+				nbytes, (int)off, err);
+			ret = err;
+			break;
+		}
+
+		buf += nbytes;
+		off += nbytes;
+		count -= nbytes;
+		ret += nbytes;
 	}
 
 	if (edev->pdata->finish)
 		edev->pdata->finish(edev);
 
 	mutex_unlock(&edev->lock);
-	return ret ? : count;
+	return ret;
 }
 
 static int eeprom_93xx46_ew(struct eeprom_93xx46_dev *edev, int is_on)
@@ -112,7 +146,13 @@ static int eeprom_93xx46_ew(struct eeprom_93xx46_dev *edev, int is_on)
 		bits = 9;
 	}
 
-	dev_dbg(&edev->spi->dev, "ew cmd 0x%04x\n", cmd_addr);
+	if (has_quirk_instruction_length(edev)) {
+		cmd_addr <<= 2;
+		bits += 2;
+	}
+
+	dev_dbg(&edev->spi->dev, "ew%s cmd 0x%04x, %d bits\n",
+			is_on ? "en" : "ds", cmd_addr, bits);
 
 	spi_message_init(&m);
 	memset(&t, 0, sizeof(t));
@@ -247,6 +287,13 @@ static int eeprom_93xx46_eral(struct eeprom_93xx46_dev *edev)
 		bits = 9;
 	}
 
+	if (has_quirk_instruction_length(edev)) {
+		cmd_addr <<= 2;
+		bits += 2;
+	}
+
+	dev_dbg(&edev->spi->dev, "eral cmd 0x%04x, %d bits\n", cmd_addr, bits);
+
 	spi_message_init(&m);
 	memset(&t, 0, sizeof(t));
 
@@ -298,12 +345,15 @@ static DEVICE_ATTR(erase, S_IWUSR, NULL, eeprom_93xx46_store_erase);
 
 static const struct of_device_id eeprom_93xx46_of_table[] = {
 	{ .compatible = "eeprom-93xx46", },
+	{ .compatible = "atmel,at93c46d", .data = &atmel_at93c46d_data, },
 	{}
 };
 MODULE_DEVICE_TABLE(of, eeprom_93xx46_of_table);
 
 static int eeprom_93xx46_probe_dt(struct spi_device *spi)
 {
+	const struct of_device_id *of_id =
+		of_match_device(eeprom_93xx46_of_table, &spi->dev);
 	struct device_node *np = spi->dev.of_node;
 	struct eeprom_93xx46_platform_data *pd;
 	u32 tmp;
@@ -331,6 +381,12 @@ static int eeprom_93xx46_probe_dt(struct spi_device *spi)
 	if (of_property_read_bool(np, "read-only"))
 		pd->flags |= EE_READONLY;
 
+	if (of_id->data) {
+		const struct eeprom_93xx46_devtype_data *data = of_id->data;
+
+		pd->quirks = data->quirks;
+	}
+
 	spi->dev.platform_data = pd;
 
 	return 0;
diff --git a/include/linux/eeprom_93xx46.h b/include/linux/eeprom_93xx46.h
index 0679181..92fa4c3 100644
--- a/include/linux/eeprom_93xx46.h
+++ b/include/linux/eeprom_93xx46.h
@@ -9,6 +9,12 @@ struct eeprom_93xx46_platform_data {
 #define EE_ADDR16	0x02		/* 16 bit addr. cfg */
 #define EE_READONLY	0x08		/* forbid writing */
 
+	unsigned int	quirks;
+/* Single word read transfers only; no sequential read. */
+#define EEPROM_93XX46_QUIRK_SINGLE_WORD_READ		(1 << 0)
+/* Instructions such as EWEN are (addrlen + 2) in length. */
+#define EEPROM_93XX46_QUIRK_INSTRUCTION_LENGTH		(1 << 1)
+
 	/*
 	 * optional hooks to control additional logic
 	 * before and after spi transfer.
-- 
2.4.10

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