i2c: I2C bus multiplexer driver pca954x
I2C driver for PCA954x I2C multiplexer series.
Signed-off-by: Michael Lawnick <ml.lawnick@gmx.de>
Acked-by: Rodolfo Giometti <giometti@linux.it>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/drivers/i2c/muxes/pca954x.c b/drivers/i2c/muxes/pca954x.c
new file mode 100644
index 0000000..6f9accf
--- /dev/null
+++ b/drivers/i2c/muxes/pca954x.c
@@ -0,0 +1,301 @@
+/*
+ * 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");