Let I2C bus segments behind multiplexers have a class. This allows for
device auto-detection on these segments. As long as parent segments
don't share the same class, it should be fine.
I implemented support in drivers i2c-mux-gpio and i2c-mux-pca954x. I
left i2c-mux-pca9541 alone for the moment as I don't know if this
feature makes sense for the use cases of that driver.
Signed-off-by: Jean Delvare <khali@xxxxxxxxxxxx>
Cc: Peter Korsgaard <peter.korsgaard@xxxxxxxxx>
Cc: David Daney <david.daney@xxxxxxxxxx>
Cc: Michael Lawnick <ml.lawnick@xxxxxx>
Cc: Rodolfo Giometti <giometti@xxxxxxxx>
---
I need this for proper support of SPD access and memory module
temperature monitoring on my Asus Z8NA-D6 board. I'll post code adding
support for SMBus multiplexing on that board later this week.
drivers/i2c/i2c-mux.c | 22 ++++++++++++++++++++++
drivers/i2c/muxes/i2c-mux-gpio.c | 4 +++-
drivers/i2c/muxes/i2c-mux-pca9541.c | 2 +-
drivers/i2c/muxes/i2c-mux-pca954x.c | 10 ++++++----
include/linux/i2c-mux-gpio.h | 2 ++
include/linux/i2c-mux.h | 1 +
include/linux/i2c/pca954x.h | 1 +
7 files changed, 36 insertions(+), 6 deletions(-)
--- linux-3.5.orig/drivers/i2c/i2c-mux.c 2012-07-24 15:01:56.000000000 +0200
+++ linux-3.5/drivers/i2c/i2c-mux.c 2012-07-24 16:38:24.994743016 +0200
@@ -88,9 +88,23 @@ static u32 i2c_mux_functionality(struct
return parent->algo->functionality(parent);
}
+/* Return all parent classes, merged */
+static unsigned int i2c_mux_parent_classes(struct i2c_adapter *parent)
+{
+ unsigned int class = 0;
+
+ do {
+ class |= parent->class;
+ parent = i2c_parent_is_i2c_adapter(parent);
+ } while (parent);
+
+ return class;
+}
+
struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
struct device *mux_dev,
void *mux_priv, u32 force_nr, u32 chan_id,
+ unsigned int class,
int (*select) (struct i2c_adapter *,
void *, u32),
int (*deselect) (struct i2c_adapter *,
@@ -127,6 +141,14 @@ struct i2c_adapter *i2c_add_mux_adapter(
priv->adap.algo_data = priv;
priv->adap.dev.parent = &parent->dev;
+ /* Sanity check on class */
+ if (i2c_mux_parent_classes(parent) & class)
+ dev_err(&parent->dev,
+ "Segment %d behind mux can't share classes with ancestors\n",
+ chan_id);
+ else
+ priv->adap.class = class;
+
/*
* Try to populate the mux adapter's of_node, expands to
* nothing if !CONFIG_OF.
--- linux-3.5.orig/drivers/i2c/muxes/i2c-mux-gpio.c 2012-07-24 15:01:56.000000000 +0200
+++ linux-3.5/drivers/i2c/muxes/i2c-mux-gpio.c 2012-07-24 15:37:44.282044411 +0200
@@ -104,8 +104,10 @@ static int __devinit i2c_mux_gpio_probe(
for (i = 0; i < pdata->n_values; i++) {
u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0;
+ unsigned int class = pdata->classes ? pdata->classes[i] : 0;
- mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr, i,
+ mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr,
+ i, class,
i2c_mux_gpio_select, deselect);
if (!mux->adap[i]) {
ret = -ENODEV;
--- linux-3.5.orig/drivers/i2c/muxes/i2c-mux-pca9541.c 2012-07-24 15:01:56.000000000 +0200
+++ linux-3.5/drivers/i2c/muxes/i2c-mux-pca9541.c 2012-07-24 15:10:00.142334435 +0200
@@ -354,7 +354,7 @@ static int pca9541_probe(struct i2c_clie
if (pdata)
force = pdata->modes[0].adap_id;
data->mux_adap = i2c_add_mux_adapter(adap, &client->dev, client,
- force, 0,
+ force, 0, 0,
pca9541_select_chan,
pca9541_release_chan);
--- linux-3.5.orig/drivers/i2c/muxes/i2c-mux-pca954x.c 2012-07-24 15:01:56.000000000 +0200
+++ linux-3.5/drivers/i2c/muxes/i2c-mux-pca954x.c 2012-07-24 15:43:41.451049259 +0200
@@ -186,7 +186,7 @@ static int pca954x_probe(struct i2c_clie
{
struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
struct pca954x_platform_data *pdata = client->dev.platform_data;
- int num, force;
+ int num, force, class;
struct pca954x *data;
int ret = -ENODEV;
@@ -216,18 +216,20 @@ static int pca954x_probe(struct i2c_clie
/* Now create an adapter for each channel */
for (num = 0; num < chips[data->type].nchans; num++) {
force = 0; /* dynamic adap number */
+ class = 0; /* no class by default */
if (pdata) {
- if (num < pdata->num_modes)
+ if (num < pdata->num_modes) {
/* force static number */
force = pdata->modes[num].adap_id;
- else
+ class = pdata->modes[num].class;
+ } else
/* discard unconfigured channels */
break;
}
data->virt_adaps[num] =
i2c_add_mux_adapter(adap, &client->dev, client,
- force, num, pca954x_select_chan,
+ force, num, class, pca954x_select_chan,
(pdata && pdata->modes[num].deselect_on_exit)
? pca954x_deselect_mux : NULL);
--- linux-3.5.orig/include/linux/i2c-mux-gpio.h 2012-07-24 15:01:56.000000000 +0200
+++ linux-3.5/include/linux/i2c-mux-gpio.h 2012-07-24 16:51:05.157982939 +0200
@@ -21,6 +21,7 @@
* @values: Array of bitmasks of GPIO settings (low/high) for each
* position
* @n_values: Number of multiplexer positions (busses to instantiate)
+ * @classes: Optional I2C auto-detection classes
* @gpios: Array of GPIO numbers used to control MUX
* @n_gpios: Number of GPIOs used to control MUX
* @idle: Bitmask to write to MUX when idle or GPIO_I2CMUX_NO_IDLE if not used
@@ -30,6 +31,7 @@ struct i2c_mux_gpio_platform_data {
int base_nr;
const unsigned *values;
int n_values;
+ const unsigned *classes;
const unsigned *gpios;
int n_gpios;
unsigned idle;
--- linux-3.5.orig/include/linux/i2c-mux.h 2012-07-24 15:01:56.000000000 +0200
+++ linux-3.5/include/linux/i2c-mux.h 2012-07-24 15:09:20.454333846 +0200
@@ -36,6 +36,7 @@
struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
struct device *mux_dev,
void *mux_priv, u32 force_nr, u32 chan_id,
+ unsigned int class,
int (*select) (struct i2c_adapter *,
void *mux_dev, u32 chan_id),
int (*deselect) (struct i2c_adapter *,
--- linux-3.5.orig/include/linux/i2c/pca954x.h 2012-07-21 22:58:29.000000000 +0200
+++ linux-3.5/include/linux/i2c/pca954x.h 2012-07-24 16:39:47.928744246 +0200
@@ -36,6 +36,7 @@
struct pca954x_platform_mode {
int adap_id;
unsigned int deselect_on_exit:1;
+ unsigned int class;
};
/* Per mux/switch data, used with i2c_register_board_info */
--
Jean Delvare
--
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