of_spi: add generic binding support to specify cs gpio (74317984) · Commits · EulixOS / Software / Kernel

Documentation/devicetree/bindings/spi/spi-bus.txt

+20 −0

Original line number	Original line	Diff line number	Diff line
	@@ -12,6 +12,7 @@ The SPI master node requires the following properties:
	- #size-cells - should be zero.		- #size-cells - should be zero.
	- compatible - name of SPI bus controller following generic names		- compatible - name of SPI bus controller following generic names
	recommended practice.		recommended practice.
			- cs-gpios - (optional) gpios chip select.
	No other properties are required in the SPI bus node. It is assumed		No other properties are required in the SPI bus node. It is assumed
	that a driver for an SPI bus device will understand that it is an SPI bus.		that a driver for an SPI bus device will understand that it is an SPI bus.
	However, the binding does not attempt to define the specific method for		However, the binding does not attempt to define the specific method for
	@@ -24,6 +25,22 @@ support describing the chip select layout.
	Optional property:		Optional property:
	- num-cs : total number of chipselects		- num-cs : total number of chipselects

			If cs-gpios is used the number of chip select will automatically increased
			with max(cs-gpios > hw cs)

			So if for example the controller has 2 CS lines, and the cs-gpios
			property looks like this:

			cs-gpios = <&gpio1 0 0> <0> <&gpio1 1 0> <&gpio1 2 0>;

			Then it should be configured so that num_chipselect = 4 with the
			following mapping:

			cs0 : &gpio1 0 0
			cs1 : native
			cs2 : &gpio1 1 0
			cs3 : &gpio1 2 0

	SPI slave nodes must be children of the SPI master node and can		SPI slave nodes must be children of the SPI master node and can
	contain the following properties.		contain the following properties.
	- reg - (required) chip select address of device.		- reg - (required) chip select address of device.
	@@ -37,6 +54,9 @@ contain the following properties.
	- spi-cs-high - (optional) Empty property indicating device requires		- spi-cs-high - (optional) Empty property indicating device requires
	chip select active high		chip select active high

			If a gpio chipselect is used for the SPI slave the gpio number will be passed
			via the cs_gpio

	SPI example for an MPC5200 SPI bus:		SPI example for an MPC5200 SPI bus:
	spi@f00 {		spi@f00 {
	#address-cells = <1>;		#address-cells = <1>;

drivers/spi/spi.c

+51 −3

Original line number	Original line	Diff line number	Diff line
	@@ -30,6 +30,7 @@
	#include <linux/slab.h>		#include <linux/slab.h>
	#include <linux/mod_devicetable.h>		#include <linux/mod_devicetable.h>
	#include <linux/spi/spi.h>		#include <linux/spi/spi.h>
			#include <linux/of_gpio.h>
	#include <linux/pm_runtime.h>		#include <linux/pm_runtime.h>
	#include <linux/export.h>		#include <linux/export.h>
	#include <linux/sched.h>		#include <linux/sched.h>
	@@ -327,6 +328,7 @@ struct spi_device spi_alloc_device(struct spi_master master)
	spi->dev.parent = &master->dev;		spi->dev.parent = &master->dev;
	spi->dev.bus = &spi_bus_type;		spi->dev.bus = &spi_bus_type;
	spi->dev.release = spidev_release;		spi->dev.release = spidev_release;
			spi->cs_gpio = -EINVAL;
	device_initialize(&spi->dev);		device_initialize(&spi->dev);
	return spi;		return spi;
	}		}
	@@ -344,15 +346,16 @@ EXPORT_SYMBOL_GPL(spi_alloc_device);
	int spi_add_device(struct spi_device *spi)		int spi_add_device(struct spi_device *spi)
	{		{
	static DEFINE_MUTEX(spi_add_lock);		static DEFINE_MUTEX(spi_add_lock);
	struct device *dev = spi->master->dev.parent;		struct spi_master *master = spi->master;
			struct device *dev = master->dev.parent;
	struct device *d;		struct device *d;
	int status;		int status;

	/* Chipselects are numbered 0..max; validate. */		/* Chipselects are numbered 0..max; validate. */
	if (spi->chip_select >= spi->master->num_chipselect) {		if (spi->chip_select >= master->num_chipselect) {
	dev_err(dev, "cs%d >= max %d\n",		dev_err(dev, "cs%d >= max %d\n",
	spi->chip_select,		spi->chip_select,
	spi->master->num_chipselect);		master->num_chipselect);
	return -EINVAL;		return -EINVAL;
	}		}

	@@ -376,6 +379,9 @@ int spi_add_device(struct spi_device *spi)
	goto done;		goto done;
	}		}

			if (master->cs_gpios)
			spi->cs_gpio = master->cs_gpios[spi->chip_select];

	/* Drivers may modify this initial i/o setup, but will		/* Drivers may modify this initial i/o setup, but will
	* normally rely on the device being setup. Devices		* normally rely on the device being setup. Devices
	* using SPI_CS_HIGH can't coexist well otherwise...		* using SPI_CS_HIGH can't coexist well otherwise...
	@@ -946,6 +952,44 @@ struct spi_master spi_alloc_master(struct device dev, unsigned size)
	}		}
	EXPORT_SYMBOL_GPL(spi_alloc_master);		EXPORT_SYMBOL_GPL(spi_alloc_master);

			#ifdef CONFIG_OF
			static int of_spi_register_master(struct spi_master *master)
			{
			u16 nb;
			int i, *cs;
			struct device_node *np = master->dev.of_node;

			if (!np)
			return 0;

			nb = of_gpio_named_count(np, "cs-gpios");
			master->num_chipselect = max(nb, master->num_chipselect);

			if (nb < 1)
			return 0;

			cs = devm_kzalloc(&master->dev,
			sizeof(int) * master->num_chipselect,
			GFP_KERNEL);
			master->cs_gpios = cs;

			if (!master->cs_gpios)
			return -ENOMEM;

			memset(cs, -EINVAL, master->num_chipselect);

			for (i = 0; i < nb; i++)
			cs[i] = of_get_named_gpio(np, "cs-gpios", i);

			return 0;
			}
			#else
			static int of_spi_register_master(struct spi_master *master)
			{
			return 0;
			}
			#endif

	/**		/**
	* spi_register_master - register SPI master controller		* spi_register_master - register SPI master controller
	* @master: initialized master, originally from spi_alloc_master()		* @master: initialized master, originally from spi_alloc_master()
	@@ -977,6 +1021,10 @@ int spi_register_master(struct spi_master *master)
	if (!dev)		if (!dev)
	return -ENODEV;		return -ENODEV;

			status = of_spi_register_master(master);
			if (status)
			return status;

	/* even if it's just one always-selected device, there must		/* even if it's just one always-selected device, there must
	* be at least one chipselect		* be at least one chipselect
	*/		*/

include/linux/spi/spi.h

+3 −0

Original line number	Original line	Diff line number	Diff line
	@@ -90,6 +90,7 @@ struct spi_device {
	void *controller_state;		void *controller_state;
	void *controller_data;		void *controller_data;
	char modalias[SPI_NAME_SIZE];		char modalias[SPI_NAME_SIZE];
			int cs_gpio; /* chip select gpio */

	/*		/*
	* likely need more hooks for more protocol options affecting how		* likely need more hooks for more protocol options affecting how
	@@ -362,6 +363,8 @@ struct spi_master {
	int (transfer_one_message)(struct spi_master master,		int (transfer_one_message)(struct spi_master master,
	struct spi_message *mesg);		struct spi_message *mesg);
	int (unprepare_transfer_hardware)(struct spi_master master);		int (unprepare_transfer_hardware)(struct spi_master master);
			/* gpio chip select */
			int *cs_gpios;
	};		};

	static inline void spi_master_get_devdata(struct spi_master master)		static inline void spi_master_get_devdata(struct spi_master master)