mfd: tqmx86: Do not access I2C_DETECT register through io_base

The I2C_DETECT register is at IO port 0x1a7, which is outside the range
passed to devm_ioport_map() for io_base, and was only working because
there aren't actually any bounds checks for IO port accesses.

Extending the range does not seem like a good solution here, as it would
then conflict with the IO resource assigned to the I2C controller. As
this is just a one-off access during probe, use a simple inb() instead.

While we're at it, drop the unused define TQMX86_REG_I2C_INT_EN.

Fixes: 2f17dd34 ("mfd: tqmx86: IO controller with I2C, Wachdog and GPIO")
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/e8300a30f0791afb67d79db8089fb6004855f378.1676892223.git.matthias.schiffer@ew.tq-group.com

drivers/mfd/tqmx86.c

@@ -49,9 +49,8 @@
 #define TQMX86_REG_IO_EXT_INT_MASK		0x3
 #define TQMX86_REG_IO_EXT_INT_GPIO_SHIFT	4
 
-#define TQMX86_REG_I2C_DETECT	0x47
+#define TQMX86_REG_I2C_DETECT	0x1a7
 #define TQMX86_REG_I2C_DETECT_SOFT		0xa5
-#define TQMX86_REG_I2C_INT_EN	0x49
 
 static uint gpio_irq;
 module_param(gpio_irq, uint, 0);
@@ -213,7 +212,12 @@ static int tqmx86_probe(struct platform_device *pdev)
 		 "Found %s - Board ID %d, PCB Revision %d, PLD Revision %d\n",
 		 board_name, board_id, rev >> 4, rev & 0xf);
 
-	i2c_det = ioread8(io_base + TQMX86_REG_I2C_DETECT);
+	/*
+	 * The I2C_DETECT register is in the range assigned to the I2C driver
+	 * later, so we don't extend TQMX86_IOSIZE. Use inb() for this one-off
+	 * access instead of ioport_map + unmap.
+	 */
+	i2c_det = inb(TQMX86_REG_I2C_DETECT);
 
 	if (gpio_irq_cfg) {
 		io_ext_int_val =