gpio: mcp23s08: convert driver to DT

This converts the mcp23s08 driver to be able to be used with
device tree.

There is a "spi-present-mask" device tree property, that allows to
use multiple of this spi chips on the same chipselect.

v4:
- removed the ability to specify the pullup from device tree
- updated binding doc

v3:
- removed mcp,chips device tree property in favour of a
    mcp,spi-present-mask and a flag for the pullup of every gpio
- seperated the match table. Now there is one for i2c and one for spi
- do the of reading stuff on stack of the probe function - no devm
    any more

v2:
- squashed booth patches together
- fixed build warning, when CONFIG_OF is not defined
- use of_match_ptr macro for of_match_table

Signed-off-by: Lars Poeschel <poeschel@lemonage.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/Documentation/devicetree/bindings/gpio/gpio-mcp23s08.txt b/Documentation/devicetree/bindings/gpio/gpio-mcp23s08.txt
new file mode 100644 (file)
index 0000000..629d0ef
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-mcp23s08.txt
@@ -0,0 +1,47 @@
+Microchip MCP2308/MCP23S08/MCP23017/MCP23S17 driver for
+8-/16-bit I/O expander with serial interface (I2C/SPI)
+
+Required properties:
+- compatible : Should be
+    - "mcp,mcp23s08" for  8 GPIO SPI version
+    - "mcp,mcp23s17" for 16 GPIO SPI version
+    - "mcp,mcp23008" for  8 GPIO I2C version or
+    - "mcp,mcp23017" for 16 GPIO I2C version of the chip
+- #gpio-cells : Should be two.
+  - first cell is the pin number
+  - second cell is used to specify flags. Flags are currently unused.
+- gpio-controller : Marks the device node as a GPIO controller.
+- reg : For an address on its bus. I2C uses this a the I2C address of the chip.
+        SPI uses this to specify the chipselect line which the chip is
+        connected to. The driver and the SPI variant of the chip support
+        multiple chips on the same chipselect. Have a look at
+        mcp,spi-present-mask below.
+
+Required device specific properties (only for SPI chips):
+- mcp,spi-present-mask : This is a present flag, that makes only sense for SPI
+        chips - as the name suggests. Multiple SPI chips can share the same
+        SPI chipselect. Set a bit in bit0-7 in this mask to 1 if there is a
+        chip connected with the corresponding spi address set. For example if
+        you have a chip with address 3 connected, you have to set bit3 to 1,
+        which is 0x08. mcp23s08 chip variant only supports bits 0-3. It is not
+        possible to mix mcp23s08 and mcp23s17 on the same chipselect. Set at
+        least one bit to 1 for SPI chips.
+- spi-max-frequency = The maximum frequency this chip is able to handle
+
+Example I2C:
+gpiom1: gpio@20 {
+        compatible = "mcp,mcp23017";
+        gpio-controller;
+        #gpio-cells = <2>;
+        reg = <0x20>;
+};
+
+Example SPI:
+gpiom1: gpio@0 {
+        compatible = "mcp,mcp23s17";
+        gpio-controller;
+        #gpio-cells = <2>;
+        spi-present-mask = <0x01>;
+        reg = <0>;
+        spi-max-frequency = <1000000>;
+};

diff --git a/drivers/gpio/gpio-mcp23s08.c b/drivers/gpio/gpio-mcp23s08.c
index 3cea0ea..6a4470b 100644 (file)
--- a/drivers/gpio/gpio-mcp23s08.c
+++ b/drivers/gpio/gpio-mcp23s08.c
@@ -12,6 +12,8 @@
 #include <linux/spi/mcp23s08.h>
 #include <linux/slab.h>
 #include <asm/byteorder.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
 
 /**
  * MCP types supported by driver
@@ -383,6 +385,10 @@ static int mcp23s08_probe_one(struct mcp23s08 *mcp, struct device *dev,
        mcp->chip.direction_output = mcp23s08_direction_output;
        mcp->chip.set = mcp23s08_set;
        mcp->chip.dbg_show = mcp23s08_dbg_show;
+#ifdef CONFIG_OF
+       mcp->chip.of_gpio_n_cells = 2;
+       mcp->chip.of_node = dev->of_node;
+#endif
 
        switch (type) {
 #ifdef CONFIG_SPI_MASTER
@@ -473,6 +479,35 @@ fail:
 
 /*----------------------------------------------------------------------*/
 
+#ifdef CONFIG_OF
+#ifdef CONFIG_SPI_MASTER
+static struct of_device_id mcp23s08_spi_of_match[] = {
+       {
+               .compatible = "mcp,mcp23s08", .data = (void *) MCP_TYPE_S08,
+       },
+       {
+               .compatible = "mcp,mcp23s17", .data = (void *) MCP_TYPE_S17,
+       },
+       { },
+};
+MODULE_DEVICE_TABLE(of, mcp23s08_spi_of_match);
+#endif
+
+#if IS_ENABLED(CONFIG_I2C)
+static struct of_device_id mcp23s08_i2c_of_match[] = {
+       {
+               .compatible = "mcp,mcp23008", .data = (void *) MCP_TYPE_008,
+       },
+       {
+               .compatible = "mcp,mcp23017", .data = (void *) MCP_TYPE_017,
+       },
+       { },
+};
+MODULE_DEVICE_TABLE(of, mcp23s08_i2c_of_match);
+#endif
+#endif /* CONFIG_OF */
+
+
 #if IS_ENABLED(CONFIG_I2C)
 
 static int mcp230xx_probe(struct i2c_client *client,
@@ -480,12 +515,23 @@ static int mcp230xx_probe(struct i2c_client *client,
 {
        struct mcp23s08_platform_data *pdata;
        struct mcp23s08 *mcp;
-       int status;
-
-       pdata = client->dev.platform_data;
-       if (!pdata || !gpio_is_valid(pdata->base)) {
-               dev_dbg(&client->dev, "invalid or missing platform data\n");
-               return -EINVAL;
+       int status, base, pullups;
+       const struct of_device_id *match;
+
+       match = of_match_device(of_match_ptr(mcp23s08_i2c_of_match),
+                                       &client->dev);
+       if (match) {
+               base = -1;
+               pullups = 0;
+       } else {
+               pdata = client->dev.platform_data;
+               if (!pdata || !gpio_is_valid(pdata->base)) {
+                       dev_dbg(&client->dev,
+                                       "invalid or missing platform data\n");
+                       return -EINVAL;
+               }
+               base = pdata->base;
+               pullups = pdata->chip[0].pullups;
        }
 
        mcp = kzalloc(sizeof *mcp, GFP_KERNEL);
@@ -493,8 +539,7 @@ static int mcp230xx_probe(struct i2c_client *client,
                return -ENOMEM;
 
        status = mcp23s08_probe_one(mcp, &client->dev, client, client->addr,
-                                   id->driver_data, pdata->base,
-                                   pdata->chip[0].pullups);
+                                   id->driver_data, base, pullups);
        if (status)
                goto fail;
 
@@ -531,6 +576,7 @@ static struct i2c_driver mcp230xx_driver = {
        .driver = {
                .name   = "mcp230xx",
                .owner  = THIS_MODULE,
+               .of_match_table = of_match_ptr(mcp23s08_i2c_of_match),
        },
        .probe          = mcp230xx_probe,
        .remove         = mcp230xx_remove,
@@ -565,28 +611,55 @@ static int mcp23s08_probe(struct spi_device *spi)
        unsigned                        chips = 0;
        struct mcp23s08_driver_data     *data;
        int                             status, type;
-       unsigned                        base;
-
-       type = spi_get_device_id(spi)->driver_data;
-
-       pdata = spi->dev.platform_data;
-       if (!pdata || !gpio_is_valid(pdata->base)) {
-               dev_dbg(&spi->dev, "invalid or missing platform data\n");
-               return -EINVAL;
-       }
+       unsigned                        base = -1,
+                                       ngpio = 0,
+                                       pullups[ARRAY_SIZE(pdata->chip)];
+       const struct                    of_device_id *match;
+       u32                             spi_present_mask = 0;
+
+       match = of_match_device(of_match_ptr(mcp23s08_spi_of_match), &spi->dev);
+       if (match) {
+               type = (int)match->data;
+               status = of_property_read_u32(spi->dev.of_node,
+                               "mcp,spi-present-mask", &spi_present_mask);
+               if (status) {
+                       dev_err(&spi->dev, "DT has no spi-present-mask\n");
+                       return -ENODEV;
+               }
+               if ((spi_present_mask <= 0) || (spi_present_mask >= 256)) {
+                       dev_err(&spi->dev, "invalid spi-present-mask\n");
+                       return -ENODEV;
+               }
 
-       for (addr = 0; addr < ARRAY_SIZE(pdata->chip); addr++) {
-               if (!pdata->chip[addr].is_present)
-                       continue;
-               chips++;
-               if ((type == MCP_TYPE_S08) && (addr > 3)) {
-                       dev_err(&spi->dev,
-                               "mcp23s08 only supports address 0..3\n");
+               for (addr = 0; addr < ARRAY_SIZE(pdata->chip); addr++)
+                       pullups[addr] = 0;
+       } else {
+               type = spi_get_device_id(spi)->driver_data;
+               pdata = spi->dev.platform_data;
+               if (!pdata || !gpio_is_valid(pdata->base)) {
+                       dev_dbg(&spi->dev,
+                                       "invalid or missing platform data\n");
                        return -EINVAL;
                }
+
+               for (addr = 0; addr < ARRAY_SIZE(pdata->chip); addr++) {
+                       if (!pdata->chip[addr].is_present)
+                               continue;
+                       chips++;
+                       if ((type == MCP_TYPE_S08) && (addr > 3)) {
+                               dev_err(&spi->dev,
+                                       "mcp23s08 only supports address 0..3\n");
+                               return -EINVAL;
+                       }
+                       spi_present_mask |= 1 << addr;
+                       pullups[addr] = pdata->chip[addr].pullups;
+               }
+
+               if (!chips)
+                       return -ENODEV;
+
+               base = pdata->base;
        }
-       if (!chips)
-               return -ENODEV;
 
        data = kzalloc(sizeof *data + chips * sizeof(struct mcp23s08),
                        GFP_KERNEL);
@@ -594,21 +667,22 @@ static int mcp23s08_probe(struct spi_device *spi)
                return -ENOMEM;
        spi_set_drvdata(spi, data);
 
-       base = pdata->base;
        for (addr = 0; addr < ARRAY_SIZE(pdata->chip); addr++) {
-               if (!pdata->chip[addr].is_present)
+               if (!(spi_present_mask & (1 << addr)))
                        continue;
                chips--;
                data->mcp[addr] = &data->chip[chips];
                status = mcp23s08_probe_one(data->mcp[addr], &spi->dev, spi,
                                            0x40 | (addr << 1), type, base,
-                                           pdata->chip[addr].pullups);
+                                           pullups[addr]);
                if (status < 0)
                        goto fail;
 
-               base += (type == MCP_TYPE_S17) ? 16 : 8;
+               if (base != -1)
+                       base += (type == MCP_TYPE_S17) ? 16 : 8;
+               ngpio += (type == MCP_TYPE_S17) ? 16 : 8;
        }
-       data->ngpio = base - pdata->base;
+       data->ngpio = ngpio;
 
        /* NOTE:  these chips have a relatively sane IRQ framework, with
         * per-signal masking and level/edge triggering.  It's not yet
@@ -668,6 +742,7 @@ static struct spi_driver mcp23s08_driver = {
        .driver = {
                .name   = "mcp23s08",
                .owner  = THIS_MODULE,
+               .of_match_table = of_match_ptr(mcp23s08_spi_of_match),
        },
 };