V4L/DVB (6126): tuner: add warning for obsolete i2c address range 0x64 thru 0x6f

The tuner module has a rather aggressive range of possible i2c addresses.

As per the specs available, it appears as if there are no 4-byte tuners that
actually use i2c addresses in the range 0x64 thru 0x6f, yet, tuner-core claims
the address range 0x60 thru 0x6f.

Allowing tuner.ko to probe these addresses can cause potential damage to
certain IR receivers, RTC chips or any other IC's that might otherwise reside
on the i2c bus using one of these addresses.

The plan is to remove these i2c addresses from the i2c address range of the
tuner module. If any devices are discovered that actually do have tuners at
one of these addresses, the newer i2c probing methods will be used to handle
those cases.

In order to collect this information and avoid any potential regressions,
the following warning has been added upon successful detection of a tuner
using an i2c address in the range 0x64 thru 0x6f:

====================== WARNING! ======================
Support for tuners in i2c address range 0x64 thru 0x6f
will soon be dropped. This message indicates that your
hardware has a {tuner name} tuner at i2c address {addr}.
To ensure continued support for your device, please
send a copy of this message, along with full dmesg
output to v4l-dvb-maintainer@linuxtv.org
Please use subject line: "obsolete tuner i2c address."
====================== WARNING! ======================
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/tuner-core.c

@@ -145,6 +145,27 @@ static void set_freq(struct i2c_client *c, unsigned long freq)
 	}
 }
 
+static void tuner_i2c_address_check(struct tuner *t)
+{
+	if ((t->type == UNSET || t->type == TUNER_ABSENT) ||
+	    ((t->i2c.addr < 0x64) || (t->i2c.addr > 0x6f)))
+		return;
+
+	tuner_warn("====================== WARNING! ======================\n");
+	tuner_warn("Support for tuners in i2c address range 0x64 thru 0x6f\n");
+	tuner_warn("will soon be dropped. This message indicates that your\n");
+	tuner_warn("hardware has a %s tuner at i2c address 0x%02x.\n",
+		   t->i2c.name, t->i2c.addr);
+	tuner_warn("To ensure continued support for your device, please\n");
+	tuner_warn("send a copy of this message, along with full dmesg\n");
+	tuner_warn("output to v4l-dvb-maintainer@linuxtv.org\n");
+	tuner_warn("Please use subject line: \"obsolete tuner i2c address.\"\n");
+	tuner_warn("driver: %s, addr: 0x%02x, type: %d (%s)\n",
+		   t->i2c.adapter->name, t->i2c.addr, t->type,
+		   tuners[t->type].name);
+	tuner_warn("====================== WARNING! ======================\n");
+}
+
 static void set_type(struct i2c_client *c, unsigned int type,
 		     unsigned int new_mode_mask, unsigned int new_config,
 		     int (*tuner_callback) (void *dev, int command,int arg))
@@ -244,6 +265,7 @@ static void set_type(struct i2c_client *c, unsigned int type,
 	tuner_dbg("%s %s I2C addr 0x%02x with type %d used for 0x%02x\n",
 		  c->adapter->name, c->driver->driver.name, c->addr << 1, type,
 		  t->mode_mask);
+	tuner_i2c_address_check(t);
 }
 
 /*