diff options
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt | 71 | ||||
| -rw-r--r-- | drivers/gpio/gpio-pcf857x.c | 44 |
2 files changed, 107 insertions, 8 deletions
diff --git a/Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt b/Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt new file mode 100644 index 0000000..d63194a --- /dev/null +++ b/Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt @@ -0,0 +1,71 @@ +* PCF857x-compatible I/O expanders + +The PCF857x-compatible chips have "quasi-bidirectional" I/O lines that can be +driven high by a pull-up current source or driven low to ground. This combines +the direction and output level into a single bit per line, which can't be read +back. We can't actually know at initialization time whether a line is configured +(a) as output and driving the signal low/high, or (b) as input and reporting a +low/high value, without knowing the last value written since the chip came out +of reset (if any). The only reliable solution for setting up line direction is +thus to do it explicitly. + +Required Properties: + + - compatible: should be one of the following. + - "maxim,max7328": For the Maxim MAX7378 + - "maxim,max7329": For the Maxim MAX7329 + - "nxp,pca8574": For the NXP PCA8574 + - "nxp,pca8575": For the NXP PCA8575 + - "nxp,pca9670": For the NXP PCA9670 + - "nxp,pca9671": For the NXP PCA9671 + - "nxp,pca9672": For the NXP PCA9672 + - "nxp,pca9673": For the NXP PCA9673 + - "nxp,pca9674": For the NXP PCA9674 + - "nxp,pca9675": For the NXP PCA9675 + - "nxp,pcf8574": For the NXP PCF8574 + - "nxp,pcf8574a": For the NXP PCF8574A + - "nxp,pcf8575": For the NXP PCF8575 + - "ti,tca9554": For the TI TCA9554 + + - reg: I2C slave address. + + - gpio-controller: Marks the device node as a gpio controller. + - #gpio-cells: Should be 2. The first cell is the GPIO number and the second + cell specifies GPIO flags, as defined in <dt-bindings/gpio/gpio.h>. Only the + GPIO_ACTIVE_HIGH and GPIO_ACTIVE_LOW flags are supported. + +Optional Properties: + + - lines-initial-states: Bitmask that specifies the initial state of each + line. When a bit is set to zero, the corresponding line will be initialized to + the input (pulled-up) state. When the bit is set to one, the line will be + initialized the the low-level output state. If the property is not specified + all lines will be initialized to the input state. + + The I/O expander can detect input state changes, and thus optionally act as + an interrupt controller. When the expander interrupt line is connected all the + following properties must be set. For more information please see the + interrupt controller device tree bindings documentation available at + Documentation/devicetree/bindings/interrupt-controller/interrupts.txt. + + - interrupt-controller: Identifies the node as an interrupt controller. + - #interrupt-cells: Number of cells to encode an interrupt source, shall be 2. + - interrupt-parent: phandle of the parent interrupt controller. + - interrupts: Interrupt specifier for the controllers interrupt. + + +Please refer to gpio.txt in this directory for details of the common GPIO +bindings used by client devices. + +Example: PCF8575 I/O expander node + + pcf8575: gpio@20 { + compatible = "nxp,pcf8575"; + reg = <0x20>; + interrupt-parent = <&irqpin2>; + interrupts = <3 0>; + gpio-controller; + #gpio-cells = <2>; + interrupt-controller; + #interrupt-cells = <2>; + }; diff --git a/drivers/gpio/gpio-pcf857x.c b/drivers/gpio/gpio-pcf857x.c index 54725a6..1535686 100644 --- a/drivers/gpio/gpio-pcf857x.c +++ b/drivers/gpio/gpio-pcf857x.c @@ -26,6 +26,8 @@ #include <linux/irqdomain.h> #include <linux/kernel.h> #include <linux/module.h> +#include <linux/of.h> +#include <linux/of_device.h> #include <linux/slab.h> #include <linux/spinlock.h> @@ -49,6 +51,27 @@ static const struct i2c_device_id pcf857x_id[] = { }; MODULE_DEVICE_TABLE(i2c, pcf857x_id); +#ifdef CONFIG_OF +static const struct of_device_id pcf857x_of_table[] = { + { .compatible = "nxp,pcf8574" }, + { .compatible = "nxp,pcf8574a" }, + { .compatible = "nxp,pca8574" }, + { .compatible = "nxp,pca9670" }, + { .compatible = "nxp,pca9672" }, + { .compatible = "nxp,pca9674" }, + { .compatible = "nxp,pcf8575" }, + { .compatible = "nxp,pca8575" }, + { .compatible = "nxp,pca9671" }, + { .compatible = "nxp,pca9673" }, + { .compatible = "nxp,pca9675" }, + { .compatible = "maxim,max7328" }, + { .compatible = "maxim,max7329" }, + { .compatible = "ti,tca9554" }, + { } +}; +MODULE_DEVICE_TABLE(of, pcf857x_of_table); +#endif + /* * The pcf857x, pca857x, and pca967x chips only expose one read and one * write register. Writing a "one" bit (to match the reset state) lets @@ -260,14 +283,18 @@ fail: static int pcf857x_probe(struct i2c_client *client, const struct i2c_device_id *id) { - struct pcf857x_platform_data *pdata; + struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev); + struct device_node *np = client->dev.of_node; struct pcf857x *gpio; + unsigned int n_latch = 0; int status; - pdata = dev_get_platdata(&client->dev); - if (!pdata) { + if (IS_ENABLED(CONFIG_OF) && np) + of_property_read_u32(np, "lines-initial-states", &n_latch); + else if (pdata) + n_latch = pdata->n_latch; + else dev_dbg(&client->dev, "no platform data\n"); - } /* Allocate, initialize, and register this gpio_chip. */ gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL); @@ -360,11 +387,11 @@ static int pcf857x_probe(struct i2c_client *client, * may cause transient glitching since it can't know the last value * written (some pins may need to be driven low). * - * Using pdata->n_latch avoids that trouble. When left initialized - * to zero, our software copy of the "latch" then matches the chip's - * all-ones reset state. Otherwise it flags pins to be driven low. + * Using n_latch avoids that trouble. When left initialized to zero, + * our software copy of the "latch" then matches the chip's all-ones + * reset state. Otherwise it flags pins to be driven low. */ - gpio->out = pdata ? ~pdata->n_latch : ~0; + gpio->out = ~n_latch; gpio->status = gpio->out; status = gpiochip_add(&gpio->chip); @@ -426,6 +453,7 @@ static struct i2c_driver pcf857x_driver = { .driver = { .name = "pcf857x", .owner = THIS_MODULE, + .of_match_table = of_match_ptr(pcf857x_of_table), }, .probe = pcf857x_probe, .remove = pcf857x_remove, |
