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    SubjectRe: [PATCH] i2c: pca954x I2C mux driver
    Date
    Any comment or acceptance of this patch?

    - k

    On Mar 30, 2006, at 5:11 PM, Kumar Gala wrote:

    > Driver for the Phillips pca954x I2C mux/switches devices. These
    > devices handle
    > the fact that a number of I2C devices have limited address
    > selection capablities
    > and systems may end up having to mux to access all the I2C devices.
    >
    > The driver uses the i2c virtual adapter support to make each mux/
    > switch port
    > look like its own i2c bus.
    >
    > Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
    >
    > ---
    > commit 735344d2f587938da9012070f881b725269c4dc9
    > tree a12c50c7f3d34b44e33397863dc7e57f8fd0e3ec
    > parent 862cbc263e3d3e44028d7465a912847cf5366163
    > author Kumar Gala <galak@kernel.crashing.org> Thu, 30 Mar 2006
    > 17:05:14 -0600
    > committer Kumar Gala <galak@kernel.crashing.org> Thu, 30 Mar 2006
    > 17:05:14 -0600
    >
    > drivers/i2c/chips/Kconfig | 10 +
    > drivers/i2c/chips/Makefile | 1
    > drivers/i2c/chips/pca954x.c | 320 ++++++++++++++++++++++++++++++++
    > +++++++++++
    > include/linux/i2c-id.h | 1
    > 4 files changed, 332 insertions(+), 0 deletions(-)
    >
    > diff --git a/drivers/i2c/chips/Kconfig b/drivers/i2c/chips/Kconfig
    > index 7aa5c38..894c95e 100644
    > --- a/drivers/i2c/chips/Kconfig
    > +++ b/drivers/i2c/chips/Kconfig
    > @@ -56,6 +56,16 @@ config SENSORS_PCA9539
    > This driver can also be built as a module. If so, the module
    > will be called pca9539.
    >
    > +config SENSORS_PCA954x
    > + tristate "Philips PCA954x I2C Mux/switches"
    > + depends on I2C && I2C_VIRT && 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.
    > +
    > config SENSORS_PCF8591
    > tristate "Philips PCF8591"
    > depends on I2C && EXPERIMENTAL
    > diff --git a/drivers/i2c/chips/Makefile b/drivers/i2c/chips/Makefile
    > index 779868e..e69190d 100644
    > --- a/drivers/i2c/chips/Makefile
    > +++ b/drivers/i2c/chips/Makefile
    > @@ -8,6 +8,7 @@ obj-$(CONFIG_SENSORS_EEPROM) += eeprom.o
    > obj-$(CONFIG_SENSORS_MAX6875) += max6875.o
    > obj-$(CONFIG_SENSORS_M41T00) += m41t00.o
    > obj-$(CONFIG_SENSORS_PCA9539) += pca9539.o
    > +obj-$(CONFIG_SENSORS_PCA954x) += pca954x.o
    > obj-$(CONFIG_SENSORS_PCF8574) += pcf8574.o
    > obj-$(CONFIG_SENSORS_PCF8591) += pcf8591.o
    > obj-$(CONFIG_ISP1301_OMAP) += isp1301_omap.o
    > diff --git a/drivers/i2c/chips/pca954x.c b/drivers/i2c/chips/pca954x.c
    > new file mode 100644
    > index 0000000..f300493
    > --- /dev/null
    > +++ b/drivers/i2c/chips/pca954x.c
    > @@ -0,0 +1,320 @@
    > +/*
    > + * pca954x.c - Part of lm_sensors, Linux kernel modules for hardware
    > + * monitoring
    > + * 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 (normally at 0x70). 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 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>, which was
    > + * based on pcf8574.c from the same project by Frodo Looijaard,
    > + * Philip Edelbrock, Dan Eaton and Aurelien Jarno.
    > + *
    > + * 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/i2c.h>
    > +#include <linux/init.h>
    > +
    > +#define PCA954X_MAX_NCHANS 8
    > +
    > +static struct i2c_driver pca954x_driver;
    > +
    > +/* Addresses to scan: none. These chip cannot be detected. */
    > +static unsigned short normal_i2c[] = { I2C_CLIENT_END };
    > +
    > +/* Chip type must normally be specified using a parameter of the form
    > + "force_pca9544=0,0x70"
    > + The following declares the possible types.
    > +*/
    > +I2C_CLIENT_INSMOD_8(pca9540, pca9542, pca9543, pca9544,
    > + pca9545, pca9546, pca9547, pca9548);
    > +
    > +struct pca954x_chipdef {
    > + enum chips type;
    > + const char *name;
    > + 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 struct pca954x_chipdef pca954x_chipdefs[] = {
    > + {
    > + .type = pca9540,
    > + .name = "pca9540",
    > + .nchans = 2,
    > + .enable = 0x4,
    > + .muxtype = pca954x_ismux,
    > + },
    > + {
    > + .type = pca9542,
    > + .name = "pca9542",
    > + .nchans = 2,
    > + .enable = 0x4,
    > + .muxtype = pca954x_ismux,
    > + },
    > + {
    > + .type = pca9543,
    > + .name = "pca9543",
    > + .nchans = 2,
    > + .enable = 0x0,
    > + .muxtype = pca954x_isswi,
    > + },
    > + {
    > + .type = pca9544,
    > + .name = "pca9544",
    > + .nchans = 4,
    > + .enable = 0x4,
    > + .muxtype = pca954x_ismux,
    > + },
    > + {
    > + .type = pca9545,
    > + .name = "pca9545",
    > + .nchans = 4,
    > + .enable = 0x0,
    > + .muxtype = pca954x_isswi,
    > + },
    > + {
    > + .type = pca9546,
    > + .name = "pca9546",
    > + .nchans = 4,
    > + .enable = 0x0,
    > + .muxtype = pca954x_isswi,
    > + },
    > + {
    > + .type = pca9547,
    > + .name = "pca9547",
    > + .nchans = 8,
    > + .enable = 0x8,
    > + .muxtype = pca954x_ismux,
    > + },
    > + {
    > + .type = pca9548,
    > + .name = "pca9548",
    > + .nchans = 8,
    > + .enable = 0x0,
    > + .muxtype = pca954x_isswi,
    > + },
    > +};
    > +
    > +struct pca954x_data {
    > + struct i2c_client client;
    > + unsigned int chip_offset;
    > + u8 last_chan;
    > + struct i2c_adapter *virt_adapters[PCA954X_MAX_NCHANS];
    > +};
    > +
    > +static int pca954x_xfer(struct i2c_adapter *adap,
    > + struct i2c_client *client, int read_write, u8 * val)
    > +{
    > + int ret = -ENODEV;
    > +
    > + if (adap->algo->master_xfer) {
    > + struct i2c_msg msg;
    > + char buf[1];
    > +
    > + msg.addr = client->addr;
    > + msg.flags = (read_write == I2C_SMBUS_READ ? I2C_M_RD : 0);
    > + msg.len = 1;
    > + buf[0] = *val;
    > + msg.buf = buf;
    > + ret = adap->algo->master_xfer(adap, &msg, 1);
    > + } else if (adap->algo->smbus_xfer) {
    > + union i2c_smbus_data data;
    > + ret = adap->algo->smbus_xfer(adap,
    > + client->addr,
    > + client->flags & I2C_M_TEN,
    > + read_write,
    > + *val, I2C_SMBUS_BYTE, &data);
    > + }
    > +
    > + return ret;
    > +}
    > +
    > +static int pca954x_select_chan(struct i2c_adapter *adap,
    > + struct i2c_client *client, u32 chan)
    > +{
    > + struct pca954x_data *data = i2c_get_clientdata(client);
    > + struct pca954x_chipdef *chip = &pca954x_chipdefs[data->chip_offset];
    > + u8 regval = 0;
    > + 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 != chan) {
    > + ret = pca954x_xfer(adap, client, I2C_SMBUS_WRITE, &regval);
    > + data->last_chan = chan;
    > + }
    > +
    > + return ret;
    > +}
    > +
    > +static int pca954x_deselect_mux(struct i2c_adapter *adap,
    > + struct i2c_client *client, u32 value)
    > +{
    > + /* We never deselect, just stay on the last channel we selected */
    > + return 0;
    > +}
    > +
    > +static int pca954x_detect(struct i2c_adapter *bus, int address,
    > int kind)
    > +{
    > + int i, n;
    > + struct i2c_client *client;
    > + struct pca954x_data *data;
    > + int ret = -ENODEV;
    > +
    > + if (!i2c_check_functionality(bus, I2C_FUNC_SMBUS_BYTE))
    > + goto err;
    > +
    > + if (!(data = kzalloc(sizeof(struct pca954x_data), GFP_KERNEL))) {
    > + ret = -ENOMEM;
    > + goto err;
    > + }
    > +
    > + client = &data->client;
    > + client->addr = address;
    > + client->adapter = bus;
    > + client->driver = &pca954x_driver;
    > + client->flags = 0;
    > + i2c_set_clientdata(client, data);
    > + if (kind < 0) {
    > + dev_err(&bus->dev, "Attempted ill-advised probe at addr 0x%x\n",
    > + address);
    > + goto exit_free;
    > + }
    > +
    > + /* Read the mux register at addr. This does two things: it verifies
    > + that the mux is in fact present, and fetches its current
    > + contents for possible use with a future deselect algorithm.
    > + */
    > + if ((i = i2c_smbus_read_byte(client)) < 0) {
    > + dev_warn(&bus->dev, "pca954x failed to read reg at 0x%x\n",
    > + address);
    > + goto exit_free;
    > + }
    > +
    > + if (kind == any_chip) {
    > + dev_warn(&bus->dev, "pca954x needs advice on chip type - "
    > + "wildly guessing 0x%x is a PCA9540\n", address);
    > + kind = pca9540;
    > + }
    > +
    > + /* Look up in table */
    > + for (i = sizeof(pca954x_chipdefs) / sizeof(pca954x_chipdefs[0]);
    > + --i >= 0;) {
    > + if (pca954x_chipdefs[i].type == kind)
    > + break;
    > + }
    > + if (i < 0) {
    > + dev_err(&bus->dev, "Internal error: unknown kind (%d)\n", kind);
    > + goto exit_free;
    > + }
    > +
    > + data->chip_offset = i;
    > +
    > + if ((ret = i2c_attach_client(client)))
    > + goto exit_free;
    > +
    > + /* Now create virtual busses and adapters for them */
    > + for (i = 0; i < pca954x_chipdefs[data->chip_offset].nchans; i++) {
    > + data->virt_adapters[i] =
    > + i2c_add_virt_adapter(bus, client, i,
    > + &pca954x_select_chan,
    > + &pca954x_deselect_mux);
    > + if (data->virt_adapters[i] == NULL) {
    > + ret = -ENODEV;
    > + goto virt_reg_failed;
    > + }
    > + }
    > +
    > + dev_info(&client->dev,
    > + "Registered %d virtual busses for I2C %s %s\n", i,
    > + pca954x_chipdefs[data->chip_offset].muxtype == pca954x_ismux ?
    > + "mux" : "switch", pca954x_chipdefs[data->chip_offset].name);
    > +
    > + return 0;
    > +
    > +virt_reg_failed:
    > + for (n = 0; n < i; n++)
    > + i2c_del_virt_adapter(data->virt_adapters[n]);
    > + i2c_detach_client(client);
    > +exit_free:
    > + kfree(data);
    > +err:
    > + return ret;
    > +}
    > +
    > +static int pca954x_attach_adapter(struct i2c_adapter *adapter)
    > +{
    > + return i2c_probe(adapter, &addr_data, pca954x_detect);
    > +}
    > +
    > +static int pca954x_detach_client(struct i2c_client *client)
    > +{
    > + struct pca954x_data *data = i2c_get_clientdata(client);
    > + struct pca954x_chipdef *chip = &pca954x_chipdefs[data->chip_offset];
    > + int i, err;
    > +
    > + for (i = 0; i < chip->nchans; ++i) {
    > + if (data->virt_adapters[i]) {
    > + if ((err =
    > + i2c_del_virt_adapter(data->virt_adapters[i])))
    > + return err;
    > + data->virt_adapters[i] = NULL;
    > + }
    > + }
    > +
    > + if ((err = i2c_detach_client(client)))
    > + return err;
    > +
    > + kfree(data);
    > + return 0;
    > +}
    > +
    > +static struct i2c_driver pca954x_driver = {
    > + .driver = {
    > + .name = "pca954x",
    > + },
    > + .id = I2C_DRIVERID_PCA954X,
    > + .attach_adapter = pca954x_attach_adapter,
    > + .detach_client = pca954x_detach_client,
    > +};
    > +
    > +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("Kumar Gala <galak@kernel.crashing.org>");
    > +MODULE_DESCRIPTION("PCA954X I2C mux/switch driver");
    > +MODULE_LICENSE("GPL");
    > diff --git a/include/linux/i2c-id.h b/include/linux/i2c-id.h
    > index 66d5533..f8f7f20 100644
    > --- a/include/linux/i2c-id.h
    > +++ b/include/linux/i2c-id.h
    > @@ -112,6 +112,7 @@
    > #define I2C_DRIVERID_X1205 82 /* Xicor/Intersil X1205 RTC */
    > #define I2C_DRIVERID_PCF8563 83 /* Philips PCF8563 RTC */
    > #define I2C_DRIVERID_RS5C372 84 /* Ricoh RS5C372 RTC */
    > +#define I2C_DRIVERID_PCA954X 85 /* pca954x I2C mux/switch */
    >
    > #define I2C_DRIVERID_I2CDEV 900
    > #define I2C_DRIVERID_ARP 902 /* SMBus ARP
    > Client */
    >
    > -
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