i2c: I2C bus multiplexer driver pca954x (7f528135) · Commits · e / devices / android_kernel_xiaomi_markw

drivers/i2c/Kconfig

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	@@ -58,6 +58,8 @@ config I2C_MUX
	This support is also available as a module. If so, the module		This support is also available as a module. If so, the module
	will be called i2c-mux.		will be called i2c-mux.

			source drivers/i2c/muxes/Kconfig

	config I2C_HELPER_AUTO		config I2C_HELPER_AUTO
	bool "Autoselect pertinent helper modules"		bool "Autoselect pertinent helper modules"
	default y		default y

drivers/i2c/Makefile

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	@@ -7,7 +7,7 @@ obj-$(CONFIG_I2C) += i2c-core.o
	obj-$(CONFIG_I2C_SMBUS) += i2c-smbus.o		obj-$(CONFIG_I2C_SMBUS) += i2c-smbus.o
	obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o		obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o
	obj-$(CONFIG_I2C_MUX) += i2c-mux.o		obj-$(CONFIG_I2C_MUX) += i2c-mux.o
	obj-y += algos/ busses/		obj-y += algos/ busses/ muxes/

	ifeq ($(CONFIG_I2C_DEBUG_CORE),y)		ifeq ($(CONFIG_I2C_DEBUG_CORE),y)
	EXTRA_CFLAGS += -DDEBUG		EXTRA_CFLAGS += -DDEBUG

drivers/i2c/muxes/Kconfig

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			#
			# Multiplexer I2C chip drivers configuration
			#

			menu "Multiplexer I2C Chip support"
			depends on I2C_MUX

			config I2C_MUX_PCA954x
			tristate "Philips PCA954x I2C Mux/switches"
			depends on EXPERIMENTAL
			help
			If you say yes here you get support for the Philips PCA954x
			I2C mux/switch devices.

			This driver can also be built as a module. If so, the module
			will be called pca954x.

			endmenu

drivers/i2c/muxes/Makefile

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			#
			# Makefile for multiplexer I2C chip drivers.

			obj-$(CONFIG_I2C_MUX_PCA954x) += pca954x.o

			ifeq ($(CONFIG_I2C_DEBUG_BUS),y)
			EXTRA_CFLAGS += -DDEBUG
			endif

drivers/i2c/muxes/pca954x.c

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			/*
			* I2C multiplexer
			*
			* Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
			* Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
			*
			* This module supports the PCA954x series of I2C multiplexer/switch chips
			* made by Philips Semiconductors.
			* This includes the:
			* PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547
			* and PCA9548.
			*
			* These chips are all controlled via the I2C bus itself, and all have a
			* single 8-bit register. The upstream "parent" bus fans out to two,
			* four, or eight downstream busses or channels; which of these
			* are selected is determined by the chip type and register contents. A
			* mux can select only one sub-bus at a time; a switch can select any
			* combination simultaneously.
			*
			* Based on:
			* pca954x.c from Kumar Gala <galak@kernel.crashing.org>
			* Copyright (C) 2006
			*
			* Based on:
			* pca954x.c from Ken Harrenstien
			* Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
			*
			* Based on:
			* i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
			* and
			* pca9540.c from Jean Delvare <khali@linux-fr.org>.
			*
			* This file is licensed under the terms of the GNU General Public
			* License version 2. This program is licensed "as is" without any
			* warranty of any kind, whether express or implied.
			*/

			#include <linux/module.h>
			#include <linux/init.h>
			#include <linux/slab.h>
			#include <linux/device.h>
			#include <linux/i2c.h>
			#include <linux/i2c-mux.h>

			#include <linux/i2c/pca954x.h>

			#define PCA954X_MAX_NCHANS 8

			enum pca_type {
			pca_9540,
			pca_9542,
			pca_9543,
			pca_9544,
			pca_9545,
			pca_9546,
			pca_9547,
			pca_9548,
			};

			struct pca954x {
			enum pca_type type;
			struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];

			u8 last_chan; /* last register value */
			};

			struct chip_desc {
			u8 nchans;
			u8 enable; /* used for muxes only */
			enum muxtype {
			pca954x_ismux = 0,
			pca954x_isswi
			} muxtype;
			};

			/* Provide specs for the PCA954x types we know about */
			static const struct chip_desc chips[] = {
			[pca_9540] = {
			.nchans = 2,
			.enable = 0x4,
			.muxtype = pca954x_ismux,
			},
			[pca_9543] = {
			.nchans = 2,
			.muxtype = pca954x_isswi,
			},
			[pca_9544] = {
			.nchans = 4,
			.enable = 0x4,
			.muxtype = pca954x_ismux,
			},
			[pca_9545] = {
			.nchans = 4,
			.muxtype = pca954x_isswi,
			},
			[pca_9547] = {
			.nchans = 8,
			.enable = 0x8,
			.muxtype = pca954x_ismux,
			},
			[pca_9548] = {
			.nchans = 8,
			.muxtype = pca954x_isswi,
			},
			};

			static const struct i2c_device_id pca954x_id[] = {
			{ "pca9540", pca_9540 },
			{ "pca9542", pca_9540 },
			{ "pca9543", pca_9543 },
			{ "pca9544", pca_9544 },
			{ "pca9545", pca_9545 },
			{ "pca9546", pca_9545 },
			{ "pca9547", pca_9547 },
			{ "pca9548", pca_9548 },
			{ }
			};
			MODULE_DEVICE_TABLE(i2c, pca954x_id);

			/* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
			for this as they will try to lock adapter a second time */
			static int pca954x_reg_write(struct i2c_adapter *adap,
			struct i2c_client *client, u8 val)
			{
			int ret = -ENODEV;

			if (adap->algo->master_xfer) {
			struct i2c_msg msg;
			char buf[1];

			msg.addr = client->addr;
			msg.flags = 0;
			msg.len = 1;
			buf[0] = val;
			msg.buf = buf;
			ret = adap->algo->master_xfer(adap, &msg, 1);
			} else {
			union i2c_smbus_data data;
			ret = adap->algo->smbus_xfer(adap, client->addr,
			client->flags,
			I2C_SMBUS_WRITE,
			val, I2C_SMBUS_BYTE, &data);
			}

			return ret;
			}

			static int pca954x_select_chan(struct i2c_adapter *adap,
			void *client, u32 chan)
			{
			struct pca954x *data = i2c_get_clientdata(client);
			const struct chip_desc *chip = &chips[data->type];
			u8 regval;
			int ret = 0;

			/* we make switches look like muxes, not sure how to be smarter */
			if (chip->muxtype == pca954x_ismux)
			regval = chan \| chip->enable;
			else
			regval = 1 << chan;

			/* Only select the channel if its different from the last channel */
			if (data->last_chan != regval) {
			ret = pca954x_reg_write(adap, client, regval);
			data->last_chan = regval;
			}

			return ret;
			}

			static int pca954x_deselect_mux(struct i2c_adapter *adap,
			void *client, u32 chan)
			{
			struct pca954x *data = i2c_get_clientdata(client);

			/* Deselect active channel */
			data->last_chan = 0;
			return pca954x_reg_write(adap, client, data->last_chan);
			}

			/*
			* I2C init/probing/exit functions
			*/
			static int __devinit pca954x_probe(struct i2c_client *client,
			const struct i2c_device_id *id)
			{
			struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
			struct pca954x_platform_data *pdata = client->dev.platform_data;
			int num, force;
			struct pca954x *data;
			int ret = -ENODEV;

			if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
			goto err;

			data = kzalloc(sizeof(struct pca954x), GFP_KERNEL);
			if (!data) {
			ret = -ENOMEM;
			goto err;
			}

			i2c_set_clientdata(client, data);

			/* Read the mux register at addr to verify
			* that the mux is in fact present.
			*/
			if (i2c_smbus_read_byte(client) < 0) {
			dev_warn(&client->dev, "probe failed\n");
			goto exit_free;
			}

			data->type = id->driver_data;
			data->last_chan = 0; /* force the first selection */

			/* Now create an adapter for each channel */
			for (num = 0; num < chips[data->type].nchans; num++) {
			force = 0; /* dynamic adap number */
			if (pdata) {
			if (num < pdata->num_modes)
			/* force static number */
			force = pdata->modes[num].adap_id;
			else
			/* discard unconfigured channels */
			break;
			}

			data->virt_adaps[num] =
			i2c_add_mux_adapter(adap, client,
			force, num, pca954x_select_chan,
			(pdata && pdata->modes[num].deselect_on_exit)
			? pca954x_deselect_mux : NULL);

			if (data->virt_adaps[num] == NULL) {
			ret = -ENODEV;
			dev_err(&client->dev,
			"failed to register multiplexed adapter"
			" %d as bus %d\n", num, force);
			goto virt_reg_failed;
			}
			}

			dev_info(&client->dev,
			"registered %d multiplexed busses for I2C %s %s\n",
			num, chips[data->type].muxtype == pca954x_ismux
			? "mux" : "switch", client->name);

			return 0;

			virt_reg_failed:
			for (num--; num >= 0; num--)
			i2c_del_mux_adapter(data->virt_adaps[num]);
			exit_free:
			kfree(data);
			err:
			return ret;
			}

			static int __devexit pca954x_remove(struct i2c_client *client)
			{
			struct pca954x *data = i2c_get_clientdata(client);
			const struct chip_desc *chip = &chips[data->type];
			int i, err;

			for (i = 0; i < chip->nchans; ++i)
			if (data->virt_adaps[i]) {
			err = i2c_del_mux_adapter(data->virt_adaps[i]);
			if (err)
			return err;
			data->virt_adaps[i] = NULL;
			}

			kfree(data);
			return 0;
			}

			static struct i2c_driver pca954x_driver = {
			.driver = {
			.name = "pca954x",
			.owner = THIS_MODULE,
			},
			.probe = pca954x_probe,
			.remove = __devexit_p(pca954x_remove),
			.id_table = pca954x_id,
			};

			static int __init pca954x_init(void)
			{
			return i2c_add_driver(&pca954x_driver);
			}

			static void __exit pca954x_exit(void)
			{
			i2c_del_driver(&pca954x_driver);
			}

			module_init(pca954x_init);
			module_exit(pca954x_exit);

			MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
			MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
			MODULE_LICENSE("GPL v2");