linux/drivers/gpio/gpio-pcf857x.c

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/*
* Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders
*
* Copyright (C) 2007 David Brownell
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/gpio.h>
#include <linux/i2c.h>
#include <linux/platform_data/pcf857x.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#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>
static const struct i2c_device_id pcf857x_id[] = {
{ "pcf8574", 8 },
{ "pcf8574a", 8 },
{ "pca8574", 8 },
{ "pca9670", 8 },
{ "pca9672", 8 },
{ "pca9674", 8 },
{ "pcf8575", 16 },
{ "pca8575", 16 },
{ "pca9671", 16 },
{ "pca9673", 16 },
{ "pca9675", 16 },
{ "max7328", 8 },
{ "max7329", 8 },
{ }
};
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" },
{ }
};
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
* that pin be used as an input; it's not an open-drain model, but acts
* a bit like one. This is described as "quasi-bidirectional"; read the
* chip documentation for details.
*
* Many other I2C GPIO expander chips (like the pca953x models) have
* more complex register models and more conventional circuitry using
* push/pull drivers. They often use the same 0x20..0x27 addresses as
* pcf857x parts, making the "legacy" I2C driver model problematic.
*/
struct pcf857x {
struct gpio_chip chip;
struct i2c_client *client;
struct mutex lock; /* protect 'out' */
unsigned out; /* software latch */
unsigned status; /* current status */
unsigned int irq_parent;
unsigned irq_enabled; /* enabled irqs */
int (*write)(struct i2c_client *client, unsigned data);
int (*read)(struct i2c_client *client);
};
/*-------------------------------------------------------------------------*/
/* Talk to 8-bit I/O expander */
static int i2c_write_le8(struct i2c_client *client, unsigned data)
{
return i2c_smbus_write_byte(client, data);
}
static int i2c_read_le8(struct i2c_client *client)
{
return (int)i2c_smbus_read_byte(client);
}
/* Talk to 16-bit I/O expander */
static int i2c_write_le16(struct i2c_client *client, unsigned word)
{
u8 buf[2] = { word & 0xff, word >> 8, };
int status;
status = i2c_master_send(client, buf, 2);
return (status < 0) ? status : 0;
}
static int i2c_read_le16(struct i2c_client *client)
{
u8 buf[2];
int status;
status = i2c_master_recv(client, buf, 2);
if (status < 0)
return status;
return (buf[1] << 8) | buf[0];
}
/*-------------------------------------------------------------------------*/
static int pcf857x_input(struct gpio_chip *chip, unsigned offset)
{
struct pcf857x *gpio = gpiochip_get_data(chip);
int status;
mutex_lock(&gpio->lock);
gpio->out |= (1 << offset);
status = gpio->write(gpio->client, gpio->out);
mutex_unlock(&gpio->lock);
return status;
}
static int pcf857x_get(struct gpio_chip *chip, unsigned offset)
{
struct pcf857x *gpio = gpiochip_get_data(chip);
int value;
value = gpio->read(gpio->client);
return (value < 0) ? value : !!(value & (1 << offset));
}
static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
{
struct pcf857x *gpio = gpiochip_get_data(chip);
unsigned bit = 1 << offset;
int status;
mutex_lock(&gpio->lock);
if (value)
gpio->out |= bit;
else
gpio->out &= ~bit;
status = gpio->write(gpio->client, gpio->out);
mutex_unlock(&gpio->lock);
return status;
}
static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
{
pcf857x_output(chip, offset, value);
}
/*-------------------------------------------------------------------------*/
static irqreturn_t pcf857x_irq(int irq, void *data)
{
struct pcf857x *gpio = data;
unsigned long change, i, status;
status = gpio->read(gpio->client);
/*
* call the interrupt handler iff gpio is used as
* interrupt source, just to avoid bad irqs
*/
mutex_lock(&gpio->lock);
change = (gpio->status ^ status) & gpio->irq_enabled;
gpio->status = status;
mutex_unlock(&gpio->lock);
for_each_set_bit(i, &change, gpio->chip.ngpio)
handle_nested_irq(irq_find_mapping(gpio->chip.irqdomain, i));
return IRQ_HANDLED;
}
/*
* NOP functions
*/
static void noop(struct irq_data *data) { }
static int pcf857x_irq_set_wake(struct irq_data *data, unsigned int on)
{
struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
int error = 0;
if (gpio->irq_parent) {
error = irq_set_irq_wake(gpio->irq_parent, on);
if (error) {
dev_dbg(&gpio->client->dev,
"irq %u doesn't support irq_set_wake\n",
gpio->irq_parent);
gpio->irq_parent = 0;
}
}
return error;
}
static void pcf857x_irq_enable(struct irq_data *data)
{
struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
gpio->irq_enabled |= (1 << data->hwirq);
}
static void pcf857x_irq_disable(struct irq_data *data)
{
struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
gpio->irq_enabled &= ~(1 << data->hwirq);
}
static void pcf857x_irq_bus_lock(struct irq_data *data)
{
struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
mutex_lock(&gpio->lock);
}
static void pcf857x_irq_bus_sync_unlock(struct irq_data *data)
{
struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
mutex_unlock(&gpio->lock);
}
static struct irq_chip pcf857x_irq_chip = {
.name = "pcf857x",
.irq_enable = pcf857x_irq_enable,
.irq_disable = pcf857x_irq_disable,
.irq_ack = noop,
.irq_mask = noop,
.irq_unmask = noop,
.irq_set_wake = pcf857x_irq_set_wake,
.irq_bus_lock = pcf857x_irq_bus_lock,
.irq_bus_sync_unlock = pcf857x_irq_bus_sync_unlock,
};
/*-------------------------------------------------------------------------*/
static int pcf857x_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
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;
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);
if (!gpio)
return -ENOMEM;
mutex_init(&gpio->lock);
gpio->chip.base = pdata ? pdata->gpio_base : -1;
gpio->chip.can_sleep = true;
gpio->chip.parent = &client->dev;
gpio->chip.owner = THIS_MODULE;
gpio->chip.get = pcf857x_get;
gpio->chip.set = pcf857x_set;
gpio->chip.direction_input = pcf857x_input;
gpio->chip.direction_output = pcf857x_output;
gpio->chip.ngpio = id->driver_data;
/* NOTE: the OnSemi jlc1562b is also largely compatible with
* these parts, notably for output. It has a low-resolution
* DAC instead of pin change IRQs; and its inputs can be the
* result of comparators.
*/
/* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
* 9670, 9672, 9764, and 9764a use quite a variety.
*
* NOTE: we don't distinguish here between *4 and *4a parts.
*/
if (gpio->chip.ngpio == 8) {
gpio->write = i2c_write_le8;
gpio->read = i2c_read_le8;
if (!i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_BYTE))
status = -EIO;
/* fail if there's no chip present */
else
status = i2c_smbus_read_byte(client);
/* '75/'75c addresses are 0x20..0x27, just like the '74;
* the '75c doesn't have a current source pulling high.
* 9671, 9673, and 9765 use quite a variety of addresses.
*
* NOTE: we don't distinguish here between '75 and '75c parts.
*/
} else if (gpio->chip.ngpio == 16) {
gpio->write = i2c_write_le16;
gpio->read = i2c_read_le16;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
status = -EIO;
/* fail if there's no chip present */
else
status = i2c_read_le16(client);
} else {
dev_dbg(&client->dev, "unsupported number of gpios\n");
status = -EINVAL;
}
if (status < 0)
goto fail;
gpio->chip.label = client->name;
gpio->client = client;
i2c_set_clientdata(client, gpio);
/* NOTE: these chips have strange "quasi-bidirectional" I/O pins.
* We can't actually know whether a pin is configured (a) as output
* and driving the signal low, or (b) as input and reporting a low
* value ... without knowing the last value written since the chip
* came out of reset (if any). We can't read the latched output.
*
* In short, the only reliable solution for setting up pin direction
* is to do it explicitly. The setup() method can do that, but it
* may cause transient glitching since it can't know the last value
* written (some pins may need 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 = ~n_latch;
gpio->status = gpio->out;
status = devm_gpiochip_add_data(&client->dev, &gpio->chip, gpio);
if (status < 0)
goto fail;
/* Enable irqchip if we have an interrupt */
if (client->irq) {
gpio: simplify adding threaded interrupts This tries to simplify the use of CONFIG_GPIOLIB_IRQCHIP when using threaded interrupts: add a new call gpiochip_irqchip_add_nested() to indicate that we're dealing with a nested rather than a chained irqchip, then create a separate gpiochip_set_nested_irqchip() to mirror the gpiochip_set_chained_irqchip() call to connect the parent and child interrupts. In the nested case gpiochip_set_nested_irqchip() does nothing more than call irq_set_parent() on each valid child interrupt, which has little semantic effect in the kernel, but this is probably still formally correct. Update all drivers using nested interrupts to use gpiochip_irqchip_add_nested() so we can now see clearly which these users are. The DLN2 driver can drop its specific hack with .irq_not_threaded as we now recognize whether a chip is threaded or not from its use of gpiochip_irqchip_add_nested() signature rather than from inspecting .can_sleep. We rename the .irq_parent to .irq_chained_parent since this parent IRQ is only really kept around for the chained interrupt handlers. Cc: Lars Poeschel <poeschel@lemonage.de> Cc: Octavian Purdila <octavian.purdila@intel.com> Cc: Daniel Baluta <daniel.baluta@intel.com> Cc: Bin Gao <bin.gao@linux.intel.com> Cc: Mika Westerberg <mika.westerberg@linux.intel.com> Cc: Ajay Thomas <ajay.thomas.david.rajamanickam@intel.com> Cc: Semen Protsenko <semen.protsenko@globallogic.com> Cc: Alexander Stein <alexander.stein@systec-electronic.com> Cc: Phil Reid <preid@electromag.com.au> Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com> Cc: Patrice Chotard <patrice.chotard@st.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-11-24 10:57:25 +01:00
status = gpiochip_irqchip_add_nested(&gpio->chip,
&pcf857x_irq_chip,
0, handle_level_irq,
IRQ_TYPE_NONE);
if (status) {
dev_err(&client->dev, "cannot add irqchip\n");
goto fail;
}
status = devm_request_threaded_irq(&client->dev, client->irq,
NULL, pcf857x_irq, IRQF_ONESHOT |
IRQF_TRIGGER_FALLING | IRQF_SHARED,
dev_name(&client->dev), gpio);
if (status)
goto fail;
gpio: simplify adding threaded interrupts This tries to simplify the use of CONFIG_GPIOLIB_IRQCHIP when using threaded interrupts: add a new call gpiochip_irqchip_add_nested() to indicate that we're dealing with a nested rather than a chained irqchip, then create a separate gpiochip_set_nested_irqchip() to mirror the gpiochip_set_chained_irqchip() call to connect the parent and child interrupts. In the nested case gpiochip_set_nested_irqchip() does nothing more than call irq_set_parent() on each valid child interrupt, which has little semantic effect in the kernel, but this is probably still formally correct. Update all drivers using nested interrupts to use gpiochip_irqchip_add_nested() so we can now see clearly which these users are. The DLN2 driver can drop its specific hack with .irq_not_threaded as we now recognize whether a chip is threaded or not from its use of gpiochip_irqchip_add_nested() signature rather than from inspecting .can_sleep. We rename the .irq_parent to .irq_chained_parent since this parent IRQ is only really kept around for the chained interrupt handlers. Cc: Lars Poeschel <poeschel@lemonage.de> Cc: Octavian Purdila <octavian.purdila@intel.com> Cc: Daniel Baluta <daniel.baluta@intel.com> Cc: Bin Gao <bin.gao@linux.intel.com> Cc: Mika Westerberg <mika.westerberg@linux.intel.com> Cc: Ajay Thomas <ajay.thomas.david.rajamanickam@intel.com> Cc: Semen Protsenko <semen.protsenko@globallogic.com> Cc: Alexander Stein <alexander.stein@systec-electronic.com> Cc: Phil Reid <preid@electromag.com.au> Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com> Cc: Patrice Chotard <patrice.chotard@st.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-11-24 10:57:25 +01:00
gpiochip_set_nested_irqchip(&gpio->chip, &pcf857x_irq_chip,
client->irq);
gpio->irq_parent = client->irq;
}
/* Let platform code set up the GPIOs and their users.
* Now is the first time anyone could use them.
*/
if (pdata && pdata->setup) {
status = pdata->setup(client,
gpio->chip.base, gpio->chip.ngpio,
pdata->context);
if (status < 0)
dev_warn(&client->dev, "setup --> %d\n", status);
}
dev_info(&client->dev, "probed\n");
return 0;
fail:
dev_dbg(&client->dev, "probe error %d for '%s'\n", status,
client->name);
gpio: pcf857x: Avoid calling irq_domain_cleanup twice Currently irq_domain_cleanup is called twice if irq_domain_init fails. This causes the following crash. Unable to handle kernel paging request at virtual address 00100104 pgd = c0004000 [00100104] *pgd=00000000 Internal error: Oops: 805 [#1] SMP ARM Modules linked in: CPU: 0 PID: 6 Comm: kworker/u4:0 Not tainted 3.12.15-01889-gedd10a8-dirty #4 Workqueue: deferwq deferred_probe_work_func task: ed0ee800 ti: ed116000 task.ti: ed116000 PC is at irq_domain_remove+0x3c/0x8c LR is at 0x0 pc : [<c0089734>] lr : [<00000000>] psr: a0000013 sp : ed117b50 ip : 00100100 fp : ed117b64 r10: ed5d1a04 r9 : 00000008 r8 : 00000000 r7 : ffffffea r6 : ed5d1a20 r5 : ed5d1a00 r4 : ed5e7540 r3 : 00200200 r2 : 00100100 r1 : c08aa180 r0 : 00200200 Flags: NzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel Control: 10c53c7d Table: 8000406a DAC: 00000017 Process kworker/u4:0 (pid: 6, stack limit = 0xed116248) Stack: (0xed117b50 to 0xed118000) 7b40: 0000016b ed5d5f10 ed117b74 ed117b68 7b60: c02c8910 c0089704 ed117bb4 ed117b78 c02c8e14 c02c8900 ed5d1a04 ed5d4e80 ... <snip> ... fe0: 00000000 00000000 00000000 00000000 00000013 00000000 384a13ea 1590210a Backtrace: [<c00896f8>] (irq_domain_remove+0x0/0x8c) from [<c02c8910>] (pcf857x_irq_domain_cleanup+0x1c/0x20) r4:ed5d5f10 r3:0000016b [<c02c88f4>] (pcf857x_irq_domain_cleanup+0x0/0x20) from [<c02c8e14>] (pcf857x_probe+0x2a8/0x364) [<c02c8b6c>] (pcf857x_probe+0x0/0x364) from [<c04787ac>] (i2c_device_probe+0x80/0xc0) [<c047872c>] (i2c_device_probe+0x0/0xc0) from [<c036c33c>] (driver_probe_device+0x104/0x240) r6:00000000 r5:ed5d1a20 r4:c08c709c r3:c047872c [<c036c238>] (driver_probe_device+0x0/0x240) from [<c036c558>] (__device_attach+0x48/0x4c) r7:ed4fc480 r6:c036c510 r5:ed5d1a20 r4:c0866bb8 [<c036c510>] (__device_attach+0x0/0x4c) from [<c036a6d8>] (bus_for_each_drv+0x4c/0x94) r5:ed5d1a20 r4:00000000 [<c036a68c>] (bus_for_each_drv+0x0/0x94) from [<c036c1f4>] (device_attach+0x78/0x90) r6:c087fe50 r5:ed5d1a54 r4:ed5d1a20 [<c036c17c>] (device_attach+0x0/0x90) from [<c036b76c>] (bus_probe_device+0x8c/0xb4) r6:c087fe50 r5:ed5d1a20 r4:ed5d1a20 r3:ed17e1c0 [<c036b6e0>] (bus_probe_device+0x0/0xb4) from [<c0369888>] (device_add+0x34c/0x624) r6:ed5d1a28 r5:00000000 r4:ed5d1a20 r3:fffffffe [<c036953c>] (device_add+0x0/0x624) from [<c0369b7c>] (device_register+0x1c/0x20) ... <snip> ... [<c0060844>] (process_one_work+0x0/0x37c) from [<c0061040>] (worker_thread+0x13c/0x3c4) [<c0060f04>] (worker_thread+0x0/0x3c4) from [<c00670ec>] (kthread+0xac/0xb8) [<c0067040>] (kthread+0x0/0xb8) from [<c00148b8>] (ret_from_fork+0x14/0x3c) r7:00000000 r6:00000000 r5:c0067040 r4:ed105d20 Code: e59fc04c e591e000 e59f0048 e154000e (e5823004) ---[ end trace 59dd1e90032c4217 ]--- Signed-off-by: George Cherian <george.cherian@ti.com> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2014-05-23 07:57:26 +02:00
return status;
}
static int pcf857x_remove(struct i2c_client *client)
{
struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev);
struct pcf857x *gpio = i2c_get_clientdata(client);
int status = 0;
if (pdata && pdata->teardown) {
status = pdata->teardown(client,
gpio->chip.base, gpio->chip.ngpio,
pdata->context);
if (status < 0) {
dev_err(&client->dev, "%s --> %d\n",
"teardown", status);
return status;
}
}
return status;
}
gpio: pcf857x: restore the initial line state of all pcf lines The reset values for all the PCF lines are high and hence on shutdown we should drive all the lines high in order to bring it to the reset state. This is actually required since PCF doesn't have a reset line and even after warm reset (by invoking "reboot" in prompt) the PCF lines maintains it's previous programmed state. This becomes a problem if the boards are designed to work with the default initial state. DRA7XX_evm uses PCF8575 and one of the PCF output lines feeds to MMC/SD VDD and this line should be driven high in order for the MMC/SD to be detected. This line is modelled as regulator and the hsmmc driver takes care of enabling and disabling it. In the case of 'reboot', during shutdown path as part of it's cleanup process the hsmmc driver disables this regulator. This makes MMC *boot* not functional. Fix it by driving all the pcf lines high. This patch was sent long back (https://patchwork.ozlabs.org/patch/420382/) But there was a concern that contention might occur if the PCF shutdown handler is invoked before the shutdown handler of the PCF's consumers. In that case PCF shutdown handler can't drive all the pcf lines high without knowing if the PCF consumers are still active. However commit 52cdbdd4985 ("driver core: correct device's shutdown order") will make sure shutdown handler of PCF's consumers are invoked before invoking the shutdown handler of PCF. So it should be safe to merge this now. Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com> Signed-off-by: Sekhar Nori <nsekhar@ti.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-05-27 08:35:29 +02:00
static void pcf857x_shutdown(struct i2c_client *client)
{
struct pcf857x *gpio = i2c_get_clientdata(client);
/* Drive all the I/O lines high */
gpio->write(gpio->client, BIT(gpio->chip.ngpio) - 1);
}
static struct i2c_driver pcf857x_driver = {
.driver = {
.name = "pcf857x",
.of_match_table = of_match_ptr(pcf857x_of_table),
},
.probe = pcf857x_probe,
.remove = pcf857x_remove,
gpio: pcf857x: restore the initial line state of all pcf lines The reset values for all the PCF lines are high and hence on shutdown we should drive all the lines high in order to bring it to the reset state. This is actually required since PCF doesn't have a reset line and even after warm reset (by invoking "reboot" in prompt) the PCF lines maintains it's previous programmed state. This becomes a problem if the boards are designed to work with the default initial state. DRA7XX_evm uses PCF8575 and one of the PCF output lines feeds to MMC/SD VDD and this line should be driven high in order for the MMC/SD to be detected. This line is modelled as regulator and the hsmmc driver takes care of enabling and disabling it. In the case of 'reboot', during shutdown path as part of it's cleanup process the hsmmc driver disables this regulator. This makes MMC *boot* not functional. Fix it by driving all the pcf lines high. This patch was sent long back (https://patchwork.ozlabs.org/patch/420382/) But there was a concern that contention might occur if the PCF shutdown handler is invoked before the shutdown handler of the PCF's consumers. In that case PCF shutdown handler can't drive all the pcf lines high without knowing if the PCF consumers are still active. However commit 52cdbdd4985 ("driver core: correct device's shutdown order") will make sure shutdown handler of PCF's consumers are invoked before invoking the shutdown handler of PCF. So it should be safe to merge this now. Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com> Signed-off-by: Sekhar Nori <nsekhar@ti.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-05-27 08:35:29 +02:00
.shutdown = pcf857x_shutdown,
.id_table = pcf857x_id,
};
static int __init pcf857x_init(void)
{
return i2c_add_driver(&pcf857x_driver);
}
/* register after i2c postcore initcall and before
* subsys initcalls that may rely on these GPIOs
*/
subsys_initcall(pcf857x_init);
static void __exit pcf857x_exit(void)
{
i2c_del_driver(&pcf857x_driver);
}
module_exit(pcf857x_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Brownell");