[RFC 2/2] i2c: add pca954x bus multiplexer driver
Antony Pavlov
antonynpavlov at gmail.com
Wed Nov 18 05:00:04 PST 2015
Signed-off-by: Antony Pavlov <antonynpavlov at gmail.com>
---
drivers/i2c/Kconfig | 2 +
drivers/i2c/Makefile | 2 +-
drivers/i2c/muxes/Kconfig | 15 +++
drivers/i2c/muxes/Makefile | 4 +
drivers/i2c/muxes/pca954x.c | 254 ++++++++++++++++++++++++++++++++++++++++++++
include/i2c/i2c.h | 13 +++
6 files changed, 289 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 21cf0ec..56259d8 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -13,4 +13,6 @@ config I2C_MUX
handle multiplexed I2C bus topologies, by presenting each
multiplexed segment as a I2C adapter.
+source drivers/i2c/muxes/Kconfig
+
endif
diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index 5ce0d0a..c936534 100644
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -1,2 +1,2 @@
-obj-$(CONFIG_I2C) += i2c.o i2c-smbus.o busses/ algos/
+obj-$(CONFIG_I2C) += i2c.o i2c-smbus.o busses/ algos/ muxes/
obj-$(CONFIG_I2C_MUX) += i2c-mux.o
diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
new file mode 100644
index 0000000..c2c7048
--- /dev/null
+++ b/drivers/i2c/muxes/Kconfig
@@ -0,0 +1,15 @@
+#
+# Multiplexer I2C chip drivers configuration
+#
+
+menu "Multiplexer I2C Chip support"
+ depends on I2C_MUX
+
+config I2C_MUX_PCA954x
+ tristate "Philips PCA954x I2C Mux/switches"
+ select I2C_ALGOBIT
+ help
+ If you say yes here you get support for the Philips PCA954x
+ I2C mux/switch devices.
+
+endmenu
diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
new file mode 100644
index 0000000..4e5bd43
--- /dev/null
+++ b/drivers/i2c/muxes/Makefile
@@ -0,0 +1,4 @@
+#
+# Makefile for multiplexer I2C chip drivers.
+
+obj-$(CONFIG_I2C_MUX_PCA954x) += pca954x.o
diff --git a/drivers/i2c/muxes/pca954x.c b/drivers/i2c/muxes/pca954x.c
new file mode 100644
index 0000000..4d24fe6
--- /dev/null
+++ b/drivers/i2c/muxes/pca954x.c
@@ -0,0 +1,254 @@
+/*
+ * I2C multiplexer
+ *
+ * Copyright (c) 2008-2009 Rodolfo Giometti <giometti at linux.it>
+ * Copyright (c) 2008-2009 Eurotech S.p.A. <info at 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 at 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 at yahoo.com>
+ * and
+ * pca9540.c from Jean Delvare <khali at 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 <common.h>
+#include <driver.h>
+#include <malloc.h>
+#include <i2c/i2c.h>
+#include <i2c/i2c-algo-bit.h>
+#include <i2c/i2c-mux.h>
+#include <init.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 struct platform_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 },
+ { }
+};
+
+/* 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->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->master_xfer(adap, &msg, 1);
+ } else {
+ union i2c_smbus_data data;
+ ret = i2c_smbus_xfer(adap, client->addr,
+ 0 /* 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;
+}
+
+/*
+ * I2C init/probing/exit functions
+ */
+static int pca954x_probe(struct device_d *dev)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
+ int num, force;
+ struct pca954x *data;
+ int ret = -ENODEV;
+
+ 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;
+ }
+
+ {
+ int err;
+
+ err = dev_get_drvdata(dev, (const void **)&data->type);
+ if (err)
+ return err;
+
+ }
+
+ 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 */
+
+ data->virt_adaps[num] =
+ i2c_add_mux_adapter(adap, &client->dev, client,
+ force, num, pca954x_select_chan, 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\n",
+ num, chips[data->type].muxtype == pca954x_ismux
+ ? "mux" : "switch");
+
+ 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 struct driver_d pca954x_driver = {
+ .name = "pca954x",
+ .probe = pca954x_probe,
+ .id_table = pca954x_id,
+};
+
+static int __init pca954x_init(void)
+{
+ return i2c_driver_register(&pca954x_driver);
+}
+device_initcall(pca954x_init);
+
+MODULE_AUTHOR("Rodolfo Giometti <giometti at linux.it>");
+MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
+MODULE_LICENSE("GPL v2");
diff --git a/include/i2c/i2c.h b/include/i2c/i2c.h
index 8f7aae9..33a4791 100644
--- a/include/i2c/i2c.h
+++ b/include/i2c/i2c.h
@@ -121,15 +121,28 @@ struct i2c_adapter {
struct i2c_bus_recovery_info *bus_recovery_info;
};
+#define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
struct i2c_client {
struct device_d dev;
struct i2c_adapter *adapter;
unsigned short addr;
+ void *driver_data; /* Driver data, set and get with
+ dev_set/get_drvdata */
};
#define to_i2c_client(a) container_of(a, struct i2c_client, dev)
+static inline void *i2c_get_clientdata(const struct i2c_client *dev)
+{
+ return dev->driver_data;
+}
+
+static inline void i2c_set_clientdata(struct i2c_client *dev, void *data)
+{
+ dev->driver_data = data;
+}
+
/*flags for the client struct: */
#define I2C_CLIENT_PEC 0x04 /* Use Packet Error Checking */
#define I2C_CLIENT_SCCB 0x9000 /* Use Omnivision SCCB protocol */
--
2.6.2
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