[PATCH] i2c: do not enable fall back to Host Notify by default

[PATCH] i2c: do not enable fall back to Host Notify by default

[Dmitry Torokhov]

Falling back unconditionally to HostNotify as primary client's interrupt
breaks some drivers which alter their functionality depending on whether
interrupt is present or not, so let's introduce a board flag telling I2C
core explicitly if we want wired interrupt or HostNotify-based one:
I2C_CLIENT_HOST_NOTIFY.

For DT-based systems we introduce "host-notify" property that we convert
to I2C_CLIENT_HOST_NOTIFY board flag.

Tested-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 Documentation/devicetree/bindings/i2c/i2c.txt |  8 ++++++++
 drivers/i2c/i2c-core.c                        | 17 ++++++++---------
 include/linux/i2c.h                           |  1 +
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt
index 5fa691e6f638..cee9d5055fa2 100644
--- a/Documentation/devicetree/bindings/i2c/i2c.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c.txt
@@ -62,6 +62,9 @@ wants to support one of the below features, it should adapt the bindings below.
 	"irq" and "wakeup" names are recognized by I2C core, other names are
 	left to individual drivers.
 
+- host-notify
+	device uses SMBus host notify protocol instead of interrupt line.
+
 - multi-master
 	states that there is another master active on this bus. The OS can use
 	this information to adapt power management to keep the arbitration awake
@@ -81,6 +84,11 @@ Binding may contain optional "interrupts" property, describing interrupts
 used by the device. I2C core will assign "irq" interrupt (or the very first
 interrupt if not using interrupt names) as primary interrupt for the slave.
 
+Alternatively, devices supporting SMbus Host Notify, and connected to
+adapters that support this feature, may use "host-notify" property. I2C
+core will create a virtual interrupt for Host Notify and assign it as
+primary interrupt for the slave.
+
 Also, if device is marked as a wakeup source, I2C core will set up "wakeup"
 interrupt for the device. If "wakeup" interrupt name is not present in the
 binding, then primary interrupt will be used as wakeup interrupt.
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index cf9e396d7702..fbd1db014768 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -931,7 +931,10 @@ static int i2c_device_probe(struct device *dev)
 	if (!client->irq) {
 		int irq = -ENOENT;
 
-		if (dev->of_node) {
+		if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
+			dev_dbg(dev, "Using Host Notify IRQ\n");
+			irq = i2c_smbus_host_notify_to_irq(client);
+		} else if (dev->of_node) {
 			irq = of_irq_get_byname(dev->of_node, "irq");
 			if (irq == -EINVAL || irq == -ENODATA)
 				irq = of_irq_get(dev->of_node, 0);
@@ -940,14 +943,7 @@ static int i2c_device_probe(struct device *dev)
 		}
 		if (irq == -EPROBE_DEFER)
 			return irq;
-		/*
-		 * ACPI and OF did not find any useful IRQ, try to see
-		 * if Host Notify can be used.
-		 */
-		if (irq < 0) {
-			dev_dbg(dev, "Using Host Notify IRQ\n");
-			irq = i2c_smbus_host_notify_to_irq(client);
-		}
+
 		if (irq < 0)
 			irq = 0;
 
@@ -1716,6 +1712,9 @@ static struct i2c_client *of_i2c_register_device(struct i2c_adapter *adap,
 	info.of_node = of_node_get(node);
 	info.archdata = &dev_ad;
 
+	if (of_read_property_bool(node, "host-notify"))
+		info.flags |= I2C_CLIENT_HOST_NOTIFY;
+
 	if (of_get_property(node, "wakeup-source", NULL))
 		info.flags |= I2C_CLIENT_WAKE;
 
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index b2109c522dec..4b45ec46161f 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -665,6 +665,7 @@ i2c_unlock_adapter(struct i2c_adapter *adapter)
 #define I2C_CLIENT_TEN		0x10	/* we have a ten bit chip address */
 					/* Must equal I2C_M_TEN below */
 #define I2C_CLIENT_SLAVE	0x20	/* we are the slave */
+#define I2C_CLIENT_HOST_NOTIFY	0x40	/* We want to use I2C host notify */
 #define I2C_CLIENT_WAKE		0x80	/* for board_info; true iff can wake */
 #define I2C_CLIENT_SCCB		0x9000	/* Use Omnivision SCCB protocol */
 					/* Must match I2C_M_STOP|IGNORE_NAK */
-- 
2.11.0.390.gc69c2f50cf-goog


-- 
Dmitry

Re: [PATCH] i2c: do not enable fall back to Host Notify by default

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1902 bytes --]

Hi Dmitry,

[auto build test ERROR on wsa/i2c/for-next]
[also build test ERROR on v4.10-rc2 next-20170104]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dmitry-Torokhov/i2c-do-not-enable-fall-back-to-Host-Notify-by-default/20170105-095405
base:   https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git i2c/for-next
config: x86_64-randconfig-x017-201701 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   drivers/i2c/i2c-core.c: In function 'i2c_device_probe':
   drivers/i2c/i2c-core.c:934:23: error: 'I2C_CLIENT_HOST_HOTIFY' undeclared (first use in this function)
      if (client->flags & I2C_CLIENT_HOST_HOTIFY) {
                          ^~~~~~~~~~~~~~~~~~~~~~
   drivers/i2c/i2c-core.c:934:23: note: each undeclared identifier is reported only once for each function it appears in
   drivers/i2c/i2c-core.c: In function 'of_i2c_register_device':
>> drivers/i2c/i2c-core.c:1715:6: error: implicit declaration of function 'of_read_property_bool' [-Werror=implicit-function-declaration]
     if (of_read_property_bool(node, "host-notify"))
         ^~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors

vim +/of_read_property_bool +1715 drivers/i2c/i2c-core.c

  1709		}
  1710	
  1711		info.addr = addr;
  1712		info.of_node = of_node_get(node);
  1713		info.archdata = &dev_ad;
  1714	
> 1715		if (of_read_property_bool(node, "host-notify"))
  1716			info.flags |= I2C_CLIENT_HOST_NOTIFY;
  1717	
  1718		if (of_get_property(node, "wakeup-source", NULL))

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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Re: [PATCH] i2c: do not enable fall back to Host Notify by default

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1581 bytes --]

Hi Dmitry,

[auto build test ERROR on wsa/i2c/for-next]
[also build test ERROR on v4.10-rc2 next-20170104]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dmitry-Torokhov/i2c-do-not-enable-fall-back-to-Host-Notify-by-default/20170105-095405
base:   https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git i2c/for-next
config: x86_64-randconfig-x011-201701 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   drivers/i2c/i2c-core.c: In function 'i2c_device_probe':
>> drivers/i2c/i2c-core.c:934:23: error: 'I2C_CLIENT_HOST_HOTIFY' undeclared (first use in this function)
      if (client->flags & I2C_CLIENT_HOST_HOTIFY) {
                          ^~~~~~~~~~~~~~~~~~~~~~
   drivers/i2c/i2c-core.c:934:23: note: each undeclared identifier is reported only once for each function it appears in

vim +/I2C_CLIENT_HOST_HOTIFY +934 drivers/i2c/i2c-core.c

   928		if (!client)
   929			return 0;
   930	
   931		if (!client->irq) {
   932			int irq = -ENOENT;
   933	
 > 934			if (client->flags & I2C_CLIENT_HOST_HOTIFY) {
   935				dev_dbg(dev, "Using Host Notify IRQ\n");
   936				irq = i2c_smbus_host_notify_to_irq(client);
   937			} else if (dev->of_node) {

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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