[backport]: i2c mux pca954x allow management of device idle state (#177)

f1fb64b04b: driver-i2c-mux-pca954x-allow-management-of-device-idle-stat.patch (v5.2-rc1)
ddd7c492d: i2c: mux: pca954x: remove support for unused platform data (v5.2-rc1)

tested on celestica dx010

Signed-off-by: Guohan Lu lguohan@gmail.com

patch/driver-i2c-mux-pca954x-allow-management-of-device-idle-stat.patch

@@ -0,0 +1,207 @@
+From f1fb64b04bf414ab04e31ac107bb28137105c5fd Mon Sep 17 00:00:00 2001
+From: Robert Shearman <robert.shearman@att.com>
+Date: Thu, 28 Feb 2019 11:43:43 +0000
+Subject: [PATCH] i2c: mux: pca954x: allow management of device idle state via
+ sysfs
+
+The behaviour, by default, to not deselect after each transfer is
+unsafe when there is a device with an address that conflicts with
+another device on another mux on the same parent bus, and it
+may not be convenient to use devicetree to set the deselect mux,
+e.g. when running on x86_64 when ACPI is used to discover most of the
+device hierarchy.
+
+Therefore, provide the ability to set the idle state behaviour using a
+new sysfs file, idle_state as a complement to the method of
+instantiating the device via sysfs. The possible behaviours are
+disconnect, i.e. to deselect all channels from the mux, as-is (the
+default), i.e. leave the last channel selected, and set a
+predetermined channel.
+
+The current behaviour of leaving the channel as-is after each
+transaction is preserved.
+
+Signed-off-by: Robert Shearman <robert.shearman@att.com>
+Signed-off-by: Peter Rosin <peda@axentia.se>
+---
+ .../ABI/testing/sysfs-bus-i2c-devices-pca954x | 20 +++++
+ drivers/i2c/muxes/i2c-mux-pca954x.c           | 85 +++++++++++++++++--
+ 2 files changed, 97 insertions(+), 8 deletions(-)
+ create mode 100644 Documentation/ABI/testing/sysfs-bus-i2c-devices-pca954x
+
+diff --git a/Documentation/ABI/testing/sysfs-bus-i2c-devices-pca954x b/Documentation/ABI/testing/sysfs-bus-i2c-devices-pca954x
+new file mode 100644
+index 000000000000..0b0de8cd0d13
+--- /dev/null
++++ b/Documentation/ABI/testing/sysfs-bus-i2c-devices-pca954x
+@@ -0,0 +1,20 @@
++What:		/sys/bus/i2c/.../idle_state
++Date:		January 2019
++KernelVersion:	5.2
++Contact:	Robert Shearman <robert.shearman@att.com>
++Description:
++		Value that exists only for mux devices that can be
++		written to control the behaviour of the multiplexer on
++		idle. Possible values:
++		-2 - disconnect on idle, i.e. deselect the last used
++		     channel, which is useful when there is a device
++		     with an address that conflicts with another
++		     device on another mux on the same parent bus.
++		-1 - leave the mux as-is, which is the most optimal
++		     setting in terms of I2C operations and is the
++		     default mode.
++		0..<nchans> - set the mux to a predetermined channel,
++		     which is useful if there is one channel that is
++		     used almost always, and you want to reduce the
++		     latency for normal operations after rare
++		     transactions on other channels
+diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
+index e32fef560684..923aa3a5a3dc 100644
+--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
++++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
+@@ -49,6 +49,7 @@
+ #include <linux/pm.h>
+ #include <linux/slab.h>
+ #include <linux/spinlock.h>
++#include <dt-bindings/mux/mux.h>
+
+ #define PCA954X_MAX_NCHANS 8
+
+@@ -84,7 +85,9 @@ struct pca954x {
+ 	const struct chip_desc *chip;
+
+ 	u8 last_chan;		/* last register value */
+-	u8 deselect;
++	/* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */
++	s8 idle_state;
++
+ 	struct i2c_client *client;
+
+ 	struct irq_domain *irq;
+@@ -253,15 +256,71 @@ 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;
++	s8 idle_state;
++
++	idle_state = READ_ONCE(data->idle_state);
++	if (idle_state >= 0)
++		/* Set the mux back to a predetermined channel */
++		return pca954x_select_chan(muxc, idle_state);
++
++	if (idle_state == MUX_IDLE_DISCONNECT) {
++		/* Deselect active channel */
++		data->last_chan = 0;
++		return pca954x_reg_write(muxc->parent, client,
++					 data->last_chan);
++	}
+
+-	if (!(data->deselect & (1 << chan)))
+-		return 0;
++	/* otherwise leave as-is */
+
+-	/* Deselect active channel */
+-	data->last_chan = 0;
+-	return pca954x_reg_write(muxc->parent, client, data->last_chan);
++	return 0;
++}
++
++static ssize_t idle_state_show(struct device *dev,
++				    struct device_attribute *attr,
++				    char *buf)
++{
++	struct i2c_client *client = to_i2c_client(dev);
++	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
++	struct pca954x *data = i2c_mux_priv(muxc);
++
++	return sprintf(buf, "%d\n", READ_ONCE(data->idle_state));
++}
++
++static ssize_t idle_state_store(struct device *dev,
++				struct device_attribute *attr,
++				const char *buf, size_t count)
++{
++	struct i2c_client *client = to_i2c_client(dev);
++	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
++	struct pca954x *data = i2c_mux_priv(muxc);
++	int val;
++	int ret;
++
++	ret = kstrtoint(buf, 0, &val);
++	if (ret < 0)
++		return ret;
++
++	if (val != MUX_IDLE_AS_IS && val != MUX_IDLE_DISCONNECT &&
++	    (val < 0 || val >= data->chip->nchans))
++		return -EINVAL;
++
++	i2c_lock_bus(muxc->parent, I2C_LOCK_SEGMENT);
++
++	WRITE_ONCE(data->idle_state, val);
++	/*
++	 * Set the mux into a state consistent with the new
++	 * idle_state.
++	 */
++	if (data->last_chan || val != MUX_IDLE_DISCONNECT)
++		ret = pca954x_deselect_mux(muxc, 0);
++
++	i2c_unlock_bus(muxc->parent, I2C_LOCK_SEGMENT);
++
++	return ret < 0 ? ret : count;
+ }
+
++static DEVICE_ATTR_RW(idle_state);
++
+ static irqreturn_t pca954x_irq_handler(int irq, void *dev_id)
+ {
+ 	struct pca954x *data = dev_id;
+@@ -328,8 +387,11 @@ static int pca954x_irq_setup(struct i2c_mux_core *muxc)
+ static void pca954x_cleanup(struct i2c_mux_core *muxc)
+ {
+ 	struct pca954x *data = i2c_mux_priv(muxc);
++	struct i2c_client *client = data->client;
+ 	int c, irq;
+
++	device_remove_file(&client->dev, &dev_attr_idle_state);
++
+ 	if (data->irq) {
+ 		for (c = 0; c < data->chip->nchans; c++) {
+ 			irq = irq_find_mapping(data->irq, c);
+@@ -410,9 +472,12 @@ static int pca954x_probe(struct i2c_client *client,
+ 	}
+
+ 	data->last_chan = 0;		   /* force the first selection */
++	data->idle_state = MUX_IDLE_AS_IS;
+
+ 	idle_disconnect_dt = np &&
+ 		of_property_read_bool(np, "i2c-mux-idle-disconnect");
++	if (idle_disconnect_dt)
++		data->idle_state = MUX_IDLE_DISCONNECT;
+
+ 	ret = pca954x_irq_setup(muxc);
+ 	if (ret)
+@@ -420,8 +485,6 @@ static int pca954x_probe(struct i2c_client *client,
+
+ 	/* Now create an adapter for each channel */
+ 	for (num = 0; num < data->chip->nchans; num++) {
+-		data->deselect |= idle_disconnect_dt << num;
+-
+ 		ret = i2c_mux_add_adapter(muxc, 0, num, 0);
+ 		if (ret)
+ 			goto fail_cleanup;
+@@ -436,6 +499,12 @@ static int pca954x_probe(struct i2c_client *client,
+ 			goto fail_cleanup;
+ 	}
+
++	/*
++	 * The attr probably isn't going to be needed in most cases,
++	 * so don't fail completely on error.
++	 */
++	device_create_file(dev, &dev_attr_idle_state);
++
+ 	dev_info(dev, "registered %d multiplexed busses for I2C %s %s\n",
+ 		 num, data->chip->muxtype == pca954x_ismux
+ 				? "mux" : "switch", client->name);
+-- 
+2.25.1
+

patch/driver-i2c-mux-pca954x-remove-support-for-unused-platform-d.patch

@@ -0,0 +1,72 @@
+From ddd7c492d419eaf697733ba4dbad31662d355fc4 Mon Sep 17 00:00:00 2001
+
+From: Robert Shearman <robert.shearman@att.com>
+
+Subject: [PATCH] i2c: mux: pca954x: remove support for unused platform data
+
+There are no in-tree users of the pca954x platform data and the
+per-channel deselect configuration complicates efforts to export the
+configuration to user-space in a way that could be applied to other
+muxes. Therefore, remove support for the pca954x platform data.
+
+Signed-off-by: Robert Shearman <robert.shearman@att.com>
+Signed-off-by: Peter Rosin <peda@axentia.se>
+---
+ drivers/i2c/muxes/i2c-mux-pca954x.c |   23 +++--------------------
+ 1 file changed, 3 insertions(+), 20 deletions(-)
+
+diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
+index 24bd9275f..a0b6d0c18 100644
+--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
++++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
+@@ -46,7 +46,6 @@
+ #include <linux/of.h>
+ #include <linux/of_device.h>
+ #include <linux/of_irq.h>
+-#include <linux/platform_data/pca954x.h>
+ #include <linux/pm.h>
+ #include <linux/slab.h>
+ #include <linux/spinlock.h>
+@@ -348,14 +347,13 @@ 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 *dev = &client->dev;
+ 	struct device_node *np = dev->of_node;
+ 	bool idle_disconnect_dt;
+ 	struct gpio_desc *gpio;
+-	int num, force, class;
+ 	struct i2c_mux_core *muxc;
+ 	struct pca954x *data;
++	int num;
+ 	int ret;
+
+ 	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
+@@ -422,24 +420,9 @@ static int pca954x_probe(struct i2c_client *client,
+
+ 	/* 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;
++		data->deselect |= idle_disconnect_dt << num;
+
+-		ret = i2c_mux_add_adapter(muxc, force, num, class);
++		ret = i2c_mux_add_adapter(muxc, 0, num, 0);
+ 		if (ret)
+ 			goto fail_cleanup;
+ 	}

patch/driver-pca954x-i2c-mux-force-deselect-on-exit-flag.patch

@@ -8,10 +8,10 @@ From: wadelnn <wadelnn@users.noreply.github.com>
  1 file changed, 6 insertions(+), 1 deletion(-)
 
 diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
-index 24bd9275f..2906afaf5 100644
+index 431791d2f..f28d93c9c 100644
 --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
 +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
-@@ -196,6 +196,11 @@ static const struct i2c_device_id pca954x_id[] = {
+@@ -198,6 +198,11 @@ static const struct i2c_device_id pca954x_id[] = {
  };
  MODULE_DEVICE_TABLE(i2c, pca954x_id);
 
@@ -23,12 +23,12 @@ index 24bd9275f..2906afaf5 100644
  #ifdef CONFIG_OF
  static const struct of_device_id pca954x_of_match[] = {
  	{ .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
-@@ -437,7 +442,7 @@ static int pca954x_probe(struct i2c_client *client,
- 			idle_disconnect_pd = pdata->modes[num].deselect_on_exit;
- 		}
- 		data->deselect |= (idle_disconnect_pd ||
--				   idle_disconnect_dt) << num;
-+				   idle_disconnect_dt || force_deselect_on_exit) << num;
+@@ -476,7 +481,7 @@ static int pca954x_probe(struct i2c_client *client,
 
- 		ret = i2c_mux_add_adapter(muxc, force, num, class);
- 		if (ret)
+ 	idle_disconnect_dt = np &&
+ 		of_property_read_bool(np, "i2c-mux-idle-disconnect");
+-	if (idle_disconnect_dt)
++	if (idle_disconnect_dt || force_deselect_on_exit)
+ 		data->idle_state = MUX_IDLE_DISCONNECT;
+
+ 	ret = pca954x_irq_setup(muxc);

patch/series

@@ -12,6 +12,8 @@ driver-sff-8436-use-nvmem_device_read.patch
 driver-support-sff-8436-read-write-fix.patch
 driver-i2c-bus-intel-ismt-add-delay-param.patch
 driver-i2c-ocores-5-1.patch
+driver-i2c-mux-pca954x-remove-support-for-unused-platform-d.patch
+driver-i2c-mux-pca954x-allow-management-of-device-idle-stat.patch
 driver-pca954x-i2c-mux-force-deselect-on-exit-flag.patch
 kernel-add-kexec-reboot-string.patch
 driver-hwmon-max6620.patch