[PATCH] spi: Master driver for NXP SC18IS602/603

[PATCH] spi: Master driver for NXP SC18IS602/603

[Guenter Roeck]

This driver adds support for NXP SC18IS602/603 I2C to SPI bus bridge.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
There is one checkatch warning:
	WARNING: please write a paragraph that describes the config symbol fully
	#101: FILE: drivers/spi/Kconfig:328:
	+config SPI_SC18IS602
I ignored it to follow the description style of other SPI master drivers.

 .../devicetree/bindings/spi/spi-sc18is602.txt      |   23 ++
 Documentation/spi/spi-sc18is602                    |   36 ++
 drivers/spi/Kconfig                                |    6 +
 drivers/spi/Makefile                               |    1 +
 drivers/spi/spi-sc18is602.c                        |  364 ++++++++++++++++++++
 include/linux/platform_data/sc18is602.h            |   19 +
 6 files changed, 449 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/spi-sc18is602.txt
 create mode 100644 Documentation/spi/spi-sc18is602
 create mode 100644 drivers/spi/spi-sc18is602.c
 create mode 100644 include/linux/platform_data/sc18is602.h

diff --git a/Documentation/devicetree/bindings/spi/spi-sc18is602.txt b/Documentation/devicetree/bindings/spi/spi-sc18is602.txt
new file mode 100644
index 0000000..02f9033
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/spi-sc18is602.txt
@@ -0,0 +1,23 @@
+NXP SC18IS602/SCIS603
+
+Required properties:
+	- compatible : Should be one of
+		"nxp,sc18is602"
+		"nxp,sc18is602b"
+		"nxp,sc18is603"
+	- reg: I2C bus address
+
+Optional properties:
+	- clock-frequency : external oscillator clock frequency. If not
+	  specified, the SC18IS602 default frequency (7372000) will be used.
+
+The clock-frequency property is relevant and needed only if the chip has an
+external oscillator (SC18IS603).
+
+Example:
+
+	sc18is603@28 {
+		compatible = "nxp,sc18is603";
+		reg = <0x28>;
+		clock-frequency = <14744000>;
+	}
diff --git a/Documentation/spi/spi-sc18is602 b/Documentation/spi/spi-sc18is602
new file mode 100644
index 0000000..a457028
--- /dev/null
+++ b/Documentation/spi/spi-sc18is602
@@ -0,0 +1,36 @@
+Kernel driver spi-sc18is602
+===========================
+
+Supported chips:
+  * NXP SI18IS602/602B/603
+    Datasheet: http://www.nxp.com/documents/data_sheet/SC18IS602_602B_603.pdf
+
+Author:
+        Guenter Roeck <linux@roeck-us.net>
+
+
+Description
+-----------
+
+This driver provides connects a NXP SC18IS602/603 I2C-bus to SPI bridge to the
+kernel's SPI core subsystem.
+
+The driver does not probe for supported chips, since the SI18IS602/603 does not
+support Chip ID registers. You will have to instantiate the devices explicitly.
+Please see Documentation/i2c/instantiating-devices for details.
+
+
+Usage Notes
+-----------
+
+This driver requires the I2C adapter driver to support raw I2C messages. I2C
+adapter drivers which can only handle the SMBus protocol are not supported.
+
+The maximum SPI message size supported by SC18IS602/603 is 200 bytes. Attempts
+to initiate longer transfers will fail with -EINVAL. EEPROM read operations and
+similar large accesses have to be split into multiple chunks of no more than
+200 bytes per SPI message (128 bytes of data per message is recommended). This
+means that programs such as "cp" or "od", which automatically use large block
+sizes to access a device, can not be used directly to read data from EEPROM.
+Programs such as dd, where the block size can be specified, should be used
+instead.
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 5f84b55..920bb4d 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -325,6 +325,12 @@ config SPI_S3C64XX
 	help
 	  SPI driver for Samsung S3C64XX and newer SoCs.
 
+config SPI_SC18IS602
+	tristate "NXP SC18IS602/602B/603 I2C to SPI bridge"
+	depends on I2C
+	help
+	  SPI driver for NXP SC18IS602/602B/603 I2C to SPI bridge.
+
 config SPI_SH_MSIOF
 	tristate "SuperH MSIOF SPI controller"
 	depends on SUPERH && HAVE_CLK
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 3920dcf..7559c98 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -51,6 +51,7 @@ obj-$(CONFIG_SPI_S3C24XX)		+= spi-s3c24xx-hw.o
 spi-s3c24xx-hw-y			:= spi-s3c24xx.o
 spi-s3c24xx-hw-$(CONFIG_SPI_S3C24XX_FIQ) += spi-s3c24xx-fiq.o
 obj-$(CONFIG_SPI_S3C64XX)		+= spi-s3c64xx.o
+obj-$(CONFIG_SPI_SC18IS602)		+= spi-sc18is602.o
 obj-$(CONFIG_SPI_SH)			+= spi-sh.o
 obj-$(CONFIG_SPI_SH_HSPI)		+= spi-sh-hspi.o
 obj-$(CONFIG_SPI_SH_MSIOF)		+= spi-sh-msiof.o
diff --git a/drivers/spi/spi-sc18is602.c b/drivers/spi/spi-sc18is602.c
new file mode 100644
index 0000000..dd98964
--- /dev/null
+++ b/drivers/spi/spi-sc18is602.c
@@ -0,0 +1,364 @@
+/*
+ * NXP SC18IS602/603 SPI driver
+ *
+ * Copyright (C) Guenter Roeck <linux@roeck-us.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/pm_runtime.h>
+#include <linux/of.h>
+#include <linux/platform_data/sc18is602.h>
+
+enum chips { sc18is602, sc18is602b, sc18is603 };
+
+#define SC18IS602_BUFSIZ		200
+#define SC18IS602_CLOCK			7372000
+
+#define SC18IS602_MODE_CPHA		BIT(2)
+#define SC18IS602_MODE_CPOL		BIT(3)
+#define SC18IS602_MODE_LSB_FIRST	BIT(5)
+#define SC18IS602_MODE_CLOCK_DIV_4	0x0
+#define SC18IS602_MODE_CLOCK_DIV_16	0x1
+#define SC18IS602_MODE_CLOCK_DIV_64	0x2
+#define SC18IS602_MODE_CLOCK_DIV_128	0x3
+
+struct sc18is602 {
+	struct spi_master	*master;
+	struct device		*dev;
+	u8			ctrl;
+	u32			freq;
+	u32			speed;
+
+	/* I2C data */
+	struct i2c_client	*client;
+	enum chips		id;
+	u8			buffer[SC18IS602_BUFSIZ + 1];
+	int			tlen;	/* Data queued for tx in buffer */
+	int			rindex;	/* Receive data index in buffer */
+};
+
+static int sc18is602_wait_ready(struct sc18is602 *hw, int len)
+{
+	int i, err;
+	int usecs = 1000000 * len / hw->speed + 1;
+	u8 dummy[1];
+
+	for (i = 0; i < 10; i++) {
+		err = i2c_master_recv(hw->client, dummy, 1);
+		if (err >= 0)
+			return 0;
+		usleep_range(usecs, usecs * 2);
+	}
+	return -ETIMEDOUT;
+}
+
+static int sc18is602_txrx(struct sc18is602 *hw, struct spi_message *msg,
+			  struct spi_transfer *t, bool do_transfer)
+{
+	unsigned int len = t->len;
+	int ret;
+
+	if (hw->tlen == 0) {
+		/* First byte (I2C command) is chip select */
+		hw->buffer[0] = 1 << msg->spi->chip_select;
+		hw->tlen = 1;
+		hw->rindex = 0;
+	}
+	/*
+	 * We can not immediately send data to the chip, since each I2C message
+	 * resembles a full SPI message (from CS active to CS inactive).
+	 * Enqueue messages up to the first read or until do_transfer is true.
+	 */
+	if (t->tx_buf) {
+		memcpy(&hw->buffer[hw->tlen], t->tx_buf, len);
+		hw->tlen += len;
+		if (t->rx_buf)
+			do_transfer = true;
+		else
+			hw->rindex = hw->tlen - 1;
+	} else if (t->rx_buf) {
+		/*
+		 * For receive-only transfers we still need to perform a dummy
+		 * write to receive data from the SPI chip.
+		 * Read data starts at the end of transmit data (minus 1 to
+		 * account for CS).
+		 */
+		hw->rindex = hw->tlen - 1;
+		memset(&hw->buffer[hw->tlen], 0, len);
+		hw->tlen += len;
+		do_transfer = true;
+	}
+
+	if (do_transfer && hw->tlen > 1) {
+		ret = sc18is602_wait_ready(hw, SC18IS602_BUFSIZ);
+		if (ret < 0)
+			return ret;
+		ret = i2c_master_send(hw->client, hw->buffer, hw->tlen);
+		if (ret < 0)
+			return ret;
+		if (ret != hw->tlen)
+			return -EIO;
+
+		if (t->rx_buf) {
+			int rlen = hw->rindex + len;
+
+			ret = sc18is602_wait_ready(hw, hw->tlen);
+			if (ret < 0)
+				return ret;
+			ret = i2c_master_recv(hw->client, hw->buffer, rlen);
+			if (ret < 0)
+				return ret;
+			if (ret != rlen)
+				return -EIO;
+			memcpy(t->rx_buf, &hw->buffer[hw->rindex], len);
+		}
+		hw->tlen = 0;
+	}
+	return len;
+}
+
+static int sc18is602_setup_transfer(struct sc18is602 *hw, u32 hz, u8 mode)
+{
+	u8 ctrl = 0;
+	int ret;
+
+	if (mode & SPI_CPHA)
+		ctrl |= SC18IS602_MODE_CPHA;
+	if (mode & SPI_CPOL)
+		ctrl |= SC18IS602_MODE_CPOL;
+	if (mode & SPI_LSB_FIRST)
+		ctrl |= SC18IS602_MODE_LSB_FIRST;
+
+	/* Find the closest clock speed */
+	if (hz >= hw->freq / 4) {
+		ctrl |= SC18IS602_MODE_CLOCK_DIV_4;
+		hw->speed = hw->freq / 4;
+	} else if (hz >= hw->freq / 16) {
+		ctrl |= SC18IS602_MODE_CLOCK_DIV_16;
+		hw->speed = hw->freq / 16;
+	} else if (hz >= hw->freq / 64) {
+		ctrl |= SC18IS602_MODE_CLOCK_DIV_64;
+		hw->speed = hw->freq / 64;
+	} else {
+		ctrl |= SC18IS602_MODE_CLOCK_DIV_128;
+		hw->speed = hw->freq / 128;
+	}
+
+	/*
+	 * Don't do anything if the control value did not change. The initial
+	 * value of 0xff for hw->ctrl ensures that the correct mode will be set
+	 * with the first call to this function.
+	 */
+	if (ctrl == hw->ctrl)
+		return 0;
+
+	ret = i2c_smbus_write_byte_data(hw->client, 0xf0, ctrl);
+	if (ret < 0)
+		return ret;
+
+	hw->ctrl = ctrl;
+
+	return 0;
+}
+
+static int sc18is602_check_transfer(struct spi_device *spi,
+				    struct spi_transfer *t, int tlen)
+{
+	int bpw;
+	uint32_t hz;
+
+	if (t && t->len + tlen > SC18IS602_BUFSIZ)
+		return -EINVAL;
+
+	bpw = spi->bits_per_word;
+	if (t && t->bits_per_word)
+		bpw = t->bits_per_word;
+	if (bpw != 8)
+		return -EINVAL;
+
+	hz = spi->max_speed_hz;
+	if (t && t->speed_hz)
+		hz = t->speed_hz;
+	if (hz == 0)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int sc18is602_transfer_one(struct spi_master *master,
+				  struct spi_message *m)
+{
+	struct sc18is602 *hw = spi_master_get_devdata(master);
+	struct spi_device *spi = m->spi;
+	struct spi_transfer *t;
+	int status = 0;
+
+	/* SC18IS602 does not support CS2 */
+	if (hw->id == sc18is602 && spi->chip_select == 2) {
+		status = -ENXIO;
+		goto error;
+	}
+
+	hw->tlen = 0;
+	list_for_each_entry(t, &m->transfers, transfer_list) {
+		u32 hz = t->speed_hz ? : spi->max_speed_hz;
+		bool do_transfer;
+
+		status = sc18is602_check_transfer(spi, t, hw->tlen);
+		if (status < 0)
+			break;
+
+		status = sc18is602_setup_transfer(hw, hz, spi->mode);
+		if (status < 0)
+			break;
+
+		do_transfer = t->cs_change || list_is_last(&t->transfer_list,
+							   &m->transfers);
+
+		if (t->len) {
+			status = sc18is602_txrx(hw, m, t, do_transfer);
+			if (status < 0)
+				break;
+			m->actual_length += status;
+		}
+		status = 0;
+
+		if (t->delay_usecs)
+			udelay(t->delay_usecs);
+	}
+error:
+	m->status = status;
+	spi_finalize_current_message(master);
+
+	return status;
+}
+
+static int sc18is602_setup(struct spi_device *spi)
+{
+	if (!spi->bits_per_word)
+		spi->bits_per_word = 8;
+
+	if (spi->mode & ~(SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST))
+		return -EINVAL;
+
+	return sc18is602_check_transfer(spi, NULL, 0);
+}
+
+static int sc18is602_probe(struct i2c_client *client,
+			   const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct device_node *np = dev->of_node;
+	struct sc18is602_platform_data *pdata = dev_get_platdata(dev);
+	struct sc18is602 *hw;
+	struct spi_master *master;
+	int error;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
+				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
+		return -ENODEV;
+
+	master = spi_alloc_master(dev, sizeof(struct sc18is602));
+	if (!master)
+		return -ENOMEM;
+
+	hw = spi_master_get_devdata(master);
+	i2c_set_clientdata(client, hw);
+
+	hw->master = master;
+	hw->client = client;
+	hw->dev = dev;
+	hw->ctrl = 0xff;
+
+	hw->id = id->driver_data;
+
+	switch (hw->id) {
+	case sc18is602:
+	case sc18is602b:
+		master->num_chipselect = 4;
+		hw->freq = SC18IS602_CLOCK;
+		break;
+	case sc18is603:
+		master->num_chipselect = 2;
+		if (pdata) {
+			hw->freq = pdata->clock_frequency;
+		} else {
+			const __be32 *val;
+			int len;
+
+			val = of_get_property(np, "clock-frequency", &len);
+			if (val && len >= sizeof(__be32))
+				hw->freq = be32_to_cpup(val);
+		}
+		if (!hw->freq)
+			hw->freq = SC18IS602_CLOCK;
+		break;
+	}
+	master->bus_num = client->adapter->nr;
+	master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST;
+	master->setup = sc18is602_setup;
+	master->transfer_one_message = sc18is602_transfer_one;
+	master->dev.of_node = np;
+
+	error = spi_register_master(master);
+	if (error)
+		goto error_reg;
+
+	return 0;
+
+error_reg:
+	spi_master_put(master);
+	return error;
+}
+
+static int sc18is602_remove(struct i2c_client *client)
+{
+	struct sc18is602 *hw = i2c_get_clientdata(client);
+	struct spi_master *master = hw->master;
+
+	spi_unregister_master(master);
+
+	return 0;
+}
+
+static const struct i2c_device_id sc18is602_id[] = {
+	{ "sc18is602", sc18is602 },
+	{ "sc18is602b", sc18is602b },
+	{ "sc18is603", sc18is603 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, sc18is602_id);
+
+static struct i2c_driver sc18is602_driver = {
+	.driver = {
+		.name = "sc18is602",
+	},
+	.probe = sc18is602_probe,
+	.remove = sc18is602_remove,
+	.id_table = sc18is602_id,
+};
+
+module_i2c_driver(sc18is602_driver);
+
+MODULE_DESCRIPTION("SC18IC602/603 SPI Master Driver");
+MODULE_AUTHOR("Guenter Roeck");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/platform_data/sc18is602.h b/include/linux/platform_data/sc18is602.h
new file mode 100644
index 0000000..997b066
--- /dev/null
+++ b/include/linux/platform_data/sc18is602.h
@@ -0,0 +1,19 @@
+/*
+ * Platform data for NXP SC18IS602/603
+ *
+ * Copyright (C) 2012 Guenter Roeck <linux@roeck-us.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * For further information, see the Documentation/spi/sc18is602 file.
+ */
+
+/**
+ * struct sc18is602_platform_data - sc18is602 info
+ * @clock_frequency		SC18IS603 oscillator frequency
+ */
+struct sc18is602_platform_data {
+	u32 clock_frequency;
+};
-- 
1.7.9.7

Re: [PATCH] spi: Master driver for NXP SC18IS602/603

[Mark Brown]

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On Sat, Aug 18, 2012 at 09:06:27AM -0700, Guenter Roeck wrote:
> This driver adds support for NXP SC18IS602/603 I2C to SPI bus bridge.
> 
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Applied, thanks.  One small thing:

> +static int sc18is602_probe(struct i2c_client *client,
> +			   const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct device_node *np = dev->of_node;
> +	struct sc18is602_platform_data *pdata = dev_get_platdata(dev);
> +	struct sc18is602 *hw;
> +	struct spi_master *master;
> +	int error;
> +
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
> +				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
> +		return -ENODEV;

This feels like the wrong thing to do here: given that the user needs to
explicitly ask for the device to be instantiated we really ought to be
one the right bus so this should be more of an error.  Not sure what I
can constructively sugget except for an error message and perhaps
returning -EINVAL though.

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Re: [PATCH] spi: Master driver for NXP SC18IS602/603

[Guenter Roeck]

On Wed, Aug 22, 2012 at 07:32:30PM +0100, Mark Brown wrote:
> On Sat, Aug 18, 2012 at 09:06:27AM -0700, Guenter Roeck wrote:
> > This driver adds support for NXP SC18IS602/603 I2C to SPI bus bridge.
> > 
> > Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> 
> Applied, thanks.  One small thing:
> 
> > +static int sc18is602_probe(struct i2c_client *client,
> > +			   const struct i2c_device_id *id)
> > +{
> > +	struct device *dev = &client->dev;
> > +	struct device_node *np = dev->of_node;
> > +	struct sc18is602_platform_data *pdata = dev_get_platdata(dev);
> > +	struct sc18is602 *hw;
> > +	struct spi_master *master;
> > +	int error;
> > +
> > +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
> > +				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
> > +		return -ENODEV;
> 
> This feels like the wrong thing to do here: given that the user needs to
> explicitly ask for the device to be instantiated we really ought to be
> one the right bus so this should be more of an error.  Not sure what I
> can constructively sugget except for an error message and perhaps
> returning -EINVAL though.

Hi Mark,

Makes sense. Changing the return value to -EINVAL results in the following
warning message from the driver subsystem.

sc18is602: probe of 7-0010 failed with error -22

I think this should be good enough, as there are other possible reasons for the
call to fail which result in similar messages. Do you want to make that change,
or should I change it and resubmit ?

Thanks,
Guenter

Re: [PATCH] spi: Master driver for NXP SC18IS602/603

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 975 bytes --]

On Wed, Aug 22, 2012 at 12:19:59PM -0700, Guenter Roeck wrote:
> On Wed, Aug 22, 2012 at 07:32:30PM +0100, Mark Brown wrote:

> > This feels like the wrong thing to do here: given that the user needs to
> > explicitly ask for the device to be instantiated we really ought to be
> > one the right bus so this should be more of an error.  Not sure what I
> > can constructively sugget except for an error message and perhaps
> > returning -EINVAL though.

> Makes sense. Changing the return value to -EINVAL results in the following
> warning message from the driver subsystem.

> sc18is602: probe of 7-0010 failed with error -22

> I think this should be good enough, as there are other possible reasons for the
> call to fail which result in similar messages. Do you want to make that change,
> or should I change it and resubmit ?

The above looks good, we don't need to go overboard - so long as it's
not a silent fail I think we're OK.  Please send an incremental change.

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