410 lines
10 KiB
C
410 lines
10 KiB
C
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/*
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* I2C multiplexer
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*
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* Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
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* Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
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* Copyright (c) 2016-2017 NVIDIA CORPORATION. All rights reserved.
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*
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* This module supports the PCA954x series of I2C multiplexer/switch chips
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* made by Philips Semiconductors.
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* This includes the:
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* PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547
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* and PCA9548.
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*
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* These chips are all controlled via the I2C bus itself, and all have a
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* single 8-bit register. The upstream "parent" bus fans out to two,
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* four, or eight downstream busses or channels; which of these
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* are selected is determined by the chip type and register contents. A
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* mux can select only one sub-bus at a time; a switch can select any
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* combination simultaneously.
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*
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* Based on:
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* pca954x.c from Kumar Gala <galak@kernel.crashing.org>
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* Copyright (C) 2006
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*
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* Based on:
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* pca954x.c from Ken Harrenstien
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* Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
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*
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* Based on:
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* i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
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* and
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* pca9540.c from Jean Delvare <jdelvare@suse.de>.
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*/
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#include <linux/device.h>
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#include <linux/gpio/consumer.h>
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#include <linux/i2c.h>
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#include <linux/i2c-mux.h>
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#include <linux/i2c/pca954x.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <linux/pm.h>
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#include <linux/slab.h>
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#include <linux/regulator/consumer.h>
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#define PCA954X_MAX_NCHANS 8
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enum pca_type {
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pca_9540,
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pca_9542,
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pca_9543,
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pca_9544,
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pca_9545,
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pca_9546,
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pca_9547,
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pca_9548,
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};
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struct chip_desc {
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u8 nchans;
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u8 enable; /* used for muxes only */
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enum muxtype {
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pca954x_ismux = 0,
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pca954x_isswi
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} muxtype;
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};
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struct pca954x {
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const struct chip_desc *chip;
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u8 last_chan; /* last register value */
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u8 deselect;
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struct i2c_client *client;
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struct regulator *vcc_reg;
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struct regulator *pullup_reg;
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};
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/* Provide specs for the PCA954x types we know about */
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static const struct chip_desc chips[] = {
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[pca_9540] = {
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.nchans = 2,
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.enable = 0x4,
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.muxtype = pca954x_ismux,
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},
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[pca_9543] = {
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.nchans = 2,
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.muxtype = pca954x_isswi,
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},
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[pca_9544] = {
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.nchans = 4,
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.enable = 0x4,
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.muxtype = pca954x_ismux,
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},
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[pca_9545] = {
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.nchans = 4,
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.muxtype = pca954x_isswi,
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},
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[pca_9546] = {
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.nchans = 4,
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.muxtype = pca954x_isswi,
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},
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[pca_9547] = {
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.nchans = 8,
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.enable = 0x8,
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.muxtype = pca954x_ismux,
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},
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[pca_9548] = {
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.nchans = 8,
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.muxtype = pca954x_isswi,
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},
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};
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static const struct i2c_device_id pca954x_id[] = {
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{ "pca9540", pca_9540 },
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{ "pca9542", pca_9540 },
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{ "pca9543", pca_9543 },
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{ "pca9544", pca_9544 },
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{ "pca9545", pca_9545 },
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{ "pca9546", pca_9546 },
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{ "pca9547", pca_9547 },
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{ "pca9548", pca_9548 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, pca954x_id);
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#ifdef CONFIG_OF
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static const struct of_device_id pca954x_of_match[] = {
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{ .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
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{ .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
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{ .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
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{ .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
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{ .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
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{ .compatible = "nxp,pca9546", .data = &chips[pca_9545] },
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{ .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
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{ .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
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{}
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};
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#endif
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/* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
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for this as they will try to lock adapter a second time */
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static int pca954x_reg_write(struct i2c_adapter *adap,
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struct i2c_client *client, u8 val)
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{
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int ret = -ENODEV;
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if (adap->algo->master_xfer) {
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struct i2c_msg msg;
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char buf[1];
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msg.addr = client->addr;
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msg.flags = 0;
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msg.len = 1;
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buf[0] = val;
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msg.buf = buf;
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ret = __i2c_transfer(adap, &msg, 1);
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if (ret >= 0 && ret != 1)
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ret = -EREMOTEIO;
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} else {
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union i2c_smbus_data data;
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ret = adap->algo->smbus_xfer(adap, client->addr,
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client->flags,
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I2C_SMBUS_WRITE,
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val, I2C_SMBUS_BYTE, &data);
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}
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return ret;
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}
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static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
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{
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struct pca954x *data = i2c_mux_priv(muxc);
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struct i2c_client *client = data->client;
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const struct chip_desc *chip = data->chip;
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u8 regval;
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int ret = 0;
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/* we make switches look like muxes, not sure how to be smarter */
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if (chip->muxtype == pca954x_ismux)
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regval = chan | chip->enable;
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else
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regval = 1 << chan;
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/* Only select the channel if its different from the last channel */
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if (data->last_chan != regval) {
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ret = pca954x_reg_write(muxc->parent, client, regval);
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data->last_chan = ret < 0 ? 0 : regval;
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}
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return ret;
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}
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static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
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{
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struct pca954x *data = i2c_mux_priv(muxc);
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struct i2c_client *client = data->client;
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if (!(data->deselect & (1 << chan)))
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return 0;
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/* Deselect active channel */
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data->last_chan = 0;
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return pca954x_reg_write(muxc->parent, client, data->last_chan);
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}
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/*
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* I2C init/probing/exit functions
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*/
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static int pca954x_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
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struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
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struct device_node *of_node = client->dev.of_node;
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bool idle_disconnect_dt;
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struct gpio_desc *gpio;
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int num, force, class;
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struct i2c_mux_core *muxc;
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struct pca954x *data;
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const struct of_device_id *match;
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int ret;
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bool fskip = false;
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int force_bus = 0;
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if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
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return -ENODEV;
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muxc = i2c_mux_alloc(adap, &client->dev,
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PCA954X_MAX_NCHANS, sizeof(*data), 0,
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pca954x_select_chan, pca954x_deselect_mux);
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if (!muxc)
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return -ENOMEM;
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data = i2c_mux_priv(muxc);
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i2c_set_clientdata(client, muxc);
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data->client = client;
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/* Get regulator pointer for pca954x vcc */
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data->vcc_reg = devm_regulator_get(&client->dev, "vcc");
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if (PTR_ERR(data->vcc_reg) == -EPROBE_DEFER)
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data->vcc_reg = NULL;
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else if (IS_ERR(data->vcc_reg)) {
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ret = PTR_ERR(data->vcc_reg);
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dev_err(&client->dev, "vcc regualtor get failed, %d\n", ret);
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return ret;
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}
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/* Get regulator pointer for pca954x vcc-pullup */
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data->pullup_reg = devm_regulator_get(&client->dev, "vcc-pullup");
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if (IS_ERR(data->pullup_reg)) {
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dev_info(&client->dev, "vcc-pullup regulator not found\n");
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data->pullup_reg = NULL;
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}
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/* Enable vcc regulator for pca954x */
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if (data->vcc_reg) {
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ret = regulator_enable(data->vcc_reg);
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if (ret < 0) {
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dev_err(&client->dev, "failed to enable vcc\n");
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return ret;
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}
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}
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/* Enable vcc-pullup regulator for pca954x */
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if (data->pullup_reg) {
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ret = regulator_enable(data->pullup_reg);
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if (ret < 0) {
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dev_err(&client->dev, "failed to enable vcc-pullup\n");
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return ret;
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}
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}
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/* Get the mux out of reset if a reset GPIO is specified. */
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gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW);
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if (IS_ERR(gpio))
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return PTR_ERR(gpio);
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if (of_property_read_u32(client->dev.of_node, "force_bus_start",
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&force_bus)) {
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dev_info(&client->dev, "%s: could not read force bus number\n",
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__func__);
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} else {
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if (force_bus > 0) {
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dev_info(&client->dev,
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"%s: forcing device bus number, start %i.\n",
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__func__, force_bus);
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}
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}
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fskip = of_property_read_bool(client->dev.of_node,
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"skip_mux_detect");
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if (fskip) {
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dev_info(&client->dev, "device detect skipped.\n");
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goto pca954x_probe_skip_detect;
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}
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/* Write the mux register at addr to verify
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* that the mux is in fact present. This also
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* initializes the mux to disconnected state.
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*/
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if (i2c_smbus_write_byte(client, 0) < 0) {
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dev_warn(&client->dev, "probe failed\n");
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return -ENODEV;
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}
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pca954x_probe_skip_detect:
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match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev);
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if (match)
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data->chip = of_device_get_match_data(&client->dev);
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else
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data->chip = &chips[id->driver_data];
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data->last_chan = 0; /* force the first selection */
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idle_disconnect_dt = of_node &&
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of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
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/* Now create an adapter for each channel */
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for (num = 0; num < data->chip->nchans; num++) {
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bool idle_disconnect_pd = false;
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force = 0; /* dynamic adap number */
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class = 0; /* no class by default */
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if (force_bus)
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force = force_bus + num;
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if (pdata) {
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if (num < pdata->num_modes) {
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/* force static number */
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force = pdata->modes[num].adap_id;
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class = pdata->modes[num].class;
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} else
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/* discard unconfigured channels */
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break;
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idle_disconnect_pd = pdata->modes[num].deselect_on_exit;
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}
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if (client->dev.of_node)
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idle_disconnect_pd = true;
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data->deselect |= (idle_disconnect_pd ||
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idle_disconnect_dt) << num;
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ret = i2c_mux_add_adapter(muxc, force, num, class);
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if (ret) {
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dev_err(&client->dev,
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"failed to register multiplexed adapter"
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" %d as bus %d\n", num, force);
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goto virt_reg_failed;
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}
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}
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dev_info(&client->dev,
|
||
|
|
"registered %d multiplexed busses for I2C %s %s\n",
|
||
|
|
num, data->chip->muxtype == pca954x_ismux
|
||
|
|
? "mux" : "switch", client->name);
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
|
||
|
|
virt_reg_failed:
|
||
|
|
i2c_mux_del_adapters(muxc);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int pca954x_remove(struct i2c_client *client)
|
||
|
|
{
|
||
|
|
struct i2c_mux_core *muxc = i2c_get_clientdata(client);
|
||
|
|
|
||
|
|
i2c_mux_del_adapters(muxc);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
#ifdef CONFIG_PM_SLEEP
|
||
|
|
static int pca954x_resume(struct device *dev)
|
||
|
|
{
|
||
|
|
struct i2c_client *client = to_i2c_client(dev);
|
||
|
|
struct i2c_mux_core *muxc = i2c_get_clientdata(client);
|
||
|
|
struct pca954x *data = i2c_mux_priv(muxc);
|
||
|
|
|
||
|
|
data->last_chan = 0;
|
||
|
|
return i2c_smbus_write_byte(client, 0);
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
|
||
|
|
static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
|
||
|
|
|
||
|
|
static struct i2c_driver pca954x_driver = {
|
||
|
|
.driver = {
|
||
|
|
.name = "pca954x",
|
||
|
|
.pm = &pca954x_pm,
|
||
|
|
.of_match_table = of_match_ptr(pca954x_of_match),
|
||
|
|
},
|
||
|
|
.probe = pca954x_probe,
|
||
|
|
.remove = pca954x_remove,
|
||
|
|
.id_table = pca954x_id,
|
||
|
|
};
|
||
|
|
|
||
|
|
module_i2c_driver(pca954x_driver);
|
||
|
|
|
||
|
|
MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
|
||
|
|
MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
|
||
|
|
MODULE_LICENSE("GPL v2");
|