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linux-stable/drivers/i2c/muxes/i2c-mux-pca954x.c
Phil Reid f2114795f7 i2c: mux: pca954x: Add interrupt controller support 
Various muxes can aggregate multiple interrupts from each i2c bus.
All of the muxes with interrupt support combine the active low irq lines
using an internal 'and' function and generate a combined active low
output. The muxes do provide the ability to read a control register to
determine which irq is active. By making the mux an irq controller isr
latency can potentially be reduced by reading the status register and
then only calling the registered isr on that bus segment.

As there is no irq masking on the mux irq are disabled until irq_unmask is
called at least once.

Signed-off-by: Phil Reid <preid@electromag.com.au>
Signed-off-by: Peter Rosin <peda@axentia.se>
2017-02-10 08:23:51 +01:00

505 lines
12 KiB
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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 <jdelvare@suse.de>.
*
* 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/acpi.h>
#include <linux/device.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/i2c-mux.h>
#include <linux/i2c/pca954x.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_irq.h>
#include <linux/pm.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#define PCA954X_MAX_NCHANS 8
#define PCA954X_IRQ_OFFSET 4
enum pca_type {
pca_9540,
pca_9542,
pca_9543,
pca_9544,
pca_9545,
pca_9546,
pca_9547,
pca_9548,
};
struct chip_desc {
u8 nchans;
u8 enable; /* used for muxes only */
u8 has_irq;
enum muxtype {
pca954x_ismux = 0,
pca954x_isswi
} muxtype;
};
struct pca954x {
const struct chip_desc *chip;
u8 last_chan; /* last register value */
u8 deselect;
struct i2c_client *client;
struct irq_domain *irq;
unsigned int irq_mask;
spinlock_t lock;
};
/* 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_9542] = {
.nchans = 2,
.enable = 0x4,
.has_irq = 1,
.muxtype = pca954x_ismux,
},
[pca_9543] = {
.nchans = 2,
.has_irq = 1,
.muxtype = pca954x_isswi,
},
[pca_9544] = {
.nchans = 4,
.enable = 0x4,
.has_irq = 1,
.muxtype = pca954x_ismux,
},
[pca_9545] = {
.nchans = 4,
.has_irq = 1,
.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_9542 },
{ "pca9543", pca_9543 },
{ "pca9544", pca_9544 },
{ "pca9545", pca_9545 },
{ "pca9546", pca_9545 },
{ "pca9547", pca_9547 },
{ "pca9548", pca_9548 },
{ }
};
MODULE_DEVICE_TABLE(i2c, pca954x_id);
#ifdef CONFIG_ACPI
static const struct acpi_device_id pca954x_acpi_ids[] = {
{ .id = "PCA9540", .driver_data = pca_9540 },
{ .id = "PCA9542", .driver_data = pca_9542 },
{ .id = "PCA9543", .driver_data = pca_9543 },
{ .id = "PCA9544", .driver_data = pca_9544 },
{ .id = "PCA9545", .driver_data = pca_9545 },
{ .id = "PCA9546", .driver_data = pca_9545 },
{ .id = "PCA9547", .driver_data = pca_9547 },
{ .id = "PCA9548", .driver_data = pca_9548 },
{ }
};
MODULE_DEVICE_TABLE(acpi, pca954x_acpi_ids);
#endif
#ifdef CONFIG_OF
static const struct of_device_id pca954x_of_match[] = {
{ .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
{ .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
{ .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
{ .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
{ .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
{ .compatible = "nxp,pca9546", .data = &chips[pca_9546] },
{ .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
{ .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
{}
};
#endif
/* 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 = __i2c_transfer(adap, &msg, 1);
if (ret >= 0 && ret != 1)
ret = -EREMOTEIO;
} 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_mux_core *muxc, u32 chan)
{
struct pca954x *data = i2c_mux_priv(muxc);
struct i2c_client *client = data->client;
const struct chip_desc *chip = data->chip;
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(muxc->parent, client, regval);
data->last_chan = ret < 0 ? 0 : regval;
}
return ret;
}
static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
{
struct pca954x *data = i2c_mux_priv(muxc);
struct i2c_client *client = data->client;
if (!(data->deselect & (1 << chan)))
return 0;
/* Deselect active channel */
data->last_chan = 0;
return pca954x_reg_write(muxc->parent, client, data->last_chan);
}
static irqreturn_t pca954x_irq_handler(int irq, void *dev_id)
{
struct pca954x *data = dev_id;
unsigned int child_irq;
int ret, i, handled = 0;
ret = i2c_smbus_read_byte(data->client);
if (ret < 0)
return IRQ_NONE;
for (i = 0; i < data->chip->nchans; i++) {
if (ret & BIT(PCA954X_IRQ_OFFSET + i)) {
child_irq = irq_linear_revmap(data->irq, i);
handle_nested_irq(child_irq);
handled++;
}
}
return handled ? IRQ_HANDLED : IRQ_NONE;
}
static void pca954x_irq_mask(struct irq_data *idata)
{
struct pca954x *data = irq_data_get_irq_chip_data(idata);
unsigned int pos = idata->hwirq;
unsigned long flags;
spin_lock_irqsave(&data->lock, flags);
data->irq_mask &= ~BIT(pos);
if (!data->irq_mask)
disable_irq(data->client->irq);
spin_unlock_irqrestore(&data->lock, flags);
}
static void pca954x_irq_unmask(struct irq_data *idata)
{
struct pca954x *data = irq_data_get_irq_chip_data(idata);
unsigned int pos = idata->hwirq;
unsigned long flags;
spin_lock_irqsave(&data->lock, flags);
if (!data->irq_mask)
enable_irq(data->client->irq);
data->irq_mask |= BIT(pos);
spin_unlock_irqrestore(&data->lock, flags);
}
static int pca954x_irq_set_type(struct irq_data *idata, unsigned int type)
{
if ((type & IRQ_TYPE_SENSE_MASK) != IRQ_TYPE_LEVEL_LOW)
return -EINVAL;
return 0;
}
static struct irq_chip pca954x_irq_chip = {
.name = "i2c-mux-pca954x",
.irq_mask = pca954x_irq_mask,
.irq_unmask = pca954x_irq_unmask,
.irq_set_type = pca954x_irq_set_type,
};
static int pca954x_irq_setup(struct i2c_mux_core *muxc)
{
struct pca954x *data = i2c_mux_priv(muxc);
struct i2c_client *client = data->client;
int c, err, irq;
if (!data->chip->has_irq || client->irq <= 0)
return 0;
spin_lock_init(&data->lock);
data->irq = irq_domain_add_linear(client->dev.of_node,
data->chip->nchans,
&irq_domain_simple_ops, data);
if (!data->irq)
return -ENODEV;
for (c = 0; c < data->chip->nchans; c++) {
irq = irq_create_mapping(data->irq, c);
irq_set_chip_data(irq, data);
irq_set_chip_and_handler(irq, &pca954x_irq_chip,
handle_simple_irq);
}
err = devm_request_threaded_irq(&client->dev, data->client->irq, NULL,
pca954x_irq_handler,
IRQF_ONESHOT | IRQF_SHARED,
"pca954x", data);
if (err)
goto err_req_irq;
disable_irq(data->client->irq);
return 0;
err_req_irq:
for (c = 0; c < data->chip->nchans; c++) {
irq = irq_find_mapping(data->irq, c);
irq_dispose_mapping(irq);
}
irq_domain_remove(data->irq);
return err;
}
/*
* I2C init/probing/exit functions
*/
static int 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 = dev_get_platdata(&client->dev);
struct device_node *of_node = client->dev.of_node;
bool idle_disconnect_dt;
struct gpio_desc *gpio;
int num, force, class;
struct i2c_mux_core *muxc;
struct pca954x *data;
const struct of_device_id *match;
int ret;
if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
return -ENODEV;
muxc = i2c_mux_alloc(adap, &client->dev,
PCA954X_MAX_NCHANS, sizeof(*data), 0,
pca954x_select_chan, pca954x_deselect_mux);
if (!muxc)
return -ENOMEM;
data = i2c_mux_priv(muxc);
i2c_set_clientdata(client, muxc);
data->client = client;
/* Get the mux out of reset if a reset GPIO is specified. */
gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW);
if (IS_ERR(gpio))
return PTR_ERR(gpio);
/* Write the mux register at addr to verify
* that the mux is in fact present. This also
* initializes the mux to disconnected state.
*/
if (i2c_smbus_write_byte(client, 0) < 0) {
dev_warn(&client->dev, "probe failed\n");
return -ENODEV;
}
match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev);
if (match)
data->chip = of_device_get_match_data(&client->dev);
else if (id)
data->chip = &chips[id->driver_data];
else {
const struct acpi_device_id *acpi_id;
acpi_id = acpi_match_device(ACPI_PTR(pca954x_acpi_ids),
&client->dev);
if (!acpi_id)
return -ENODEV;
data->chip = &chips[acpi_id->driver_data];
}
data->last_chan = 0; /* force the first selection */
idle_disconnect_dt = of_node &&
of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
ret = pca954x_irq_setup(muxc);
if (ret)
goto fail_del_adapters;
/* Now create an adapter for each channel */
for (num = 0; num < data->chip->nchans; num++) {
bool idle_disconnect_pd = false;
force = 0; /* dynamic adap number */
class = 0; /* no class by default */
if (pdata) {
if (num < pdata->num_modes) {
/* force static number */
force = pdata->modes[num].adap_id;
class = pdata->modes[num].class;
} else
/* discard unconfigured channels */
break;
idle_disconnect_pd = pdata->modes[num].deselect_on_exit;
}
data->deselect |= (idle_disconnect_pd ||
idle_disconnect_dt) << num;
ret = i2c_mux_add_adapter(muxc, force, num, class);
if (ret) {
dev_err(&client->dev,
"failed to register multiplexed adapter"
" %d as bus %d\n", num, force);
goto fail_del_adapters;
}
}
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;
fail_del_adapters:
i2c_mux_del_adapters(muxc);
return ret;
}
static int pca954x_remove(struct i2c_client *client)
{
struct i2c_mux_core *muxc = i2c_get_clientdata(client);
struct pca954x *data = i2c_mux_priv(muxc);
int c, irq;
if (data->irq) {
for (c = 0; c < data->chip->nchans; c++) {
irq = irq_find_mapping(data->irq, c);
irq_dispose_mapping(irq);
}
irq_domain_remove(data->irq);
}
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),
.acpi_match_table = ACPI_PTR(pca954x_acpi_ids),
},
.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");
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