rockchip: rk3288: Fix pinctrl for GPIO bank 0

Bank 0 is the "PMU GPIO" bank which is controlled by the PMU registers
rather than the GRF registers.  In the GRF the top half of the register
is used as a mask so that some bits can be updated without affecting the
others, but in the PMU this feature is not provided and the top half of
the register is reserved.

Take the same approach as the Linux driver to update the value via
read-modify-write but setting the mask for only the bits that have
changed.  The PMU registers ignore the top 16 bits so this works for
both GRF and PMU iomux registers.

Signed-off-by: John Keeping <john@metanate.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>

drivers/pinctrl/rockchip/pinctrl_rk3288.c

@@ -588,6 +588,7 @@ static int rk3288_pinctrl_set_pins(struct udevice *dev, int banknum, int index,
 	struct rk3288_pinctrl_priv *priv = dev_get_priv(dev);
 	uint shift, ind = index;
 	uint mask;
+	uint value;
 	u32 *addr;
 	int ret;
 
@@ -596,7 +597,18 @@ static int rk3288_pinctrl_set_pins(struct udevice *dev, int banknum, int index,
 					  &mask);
 	if (ret)
 		return ret;
-	rk_clrsetreg(addr, mask << shift, muxval << shift);
+
+	/*
+	 * PMU_GPIO0 registers cannot be selectively written so we cannot use
+	 * rk_clrsetreg() here.  However, the upper 16 bits are reserved and
+	 * are ignored when written, so we can use the same code as for the
+	 * other GPIO banks providing that we preserve the value of the other
+	 * bits.
+	 */
+	value = readl(addr);
+	value &= ~(mask << shift);
+	value |= (mask << (shift + 16)) | (muxval << shift);
+	writel(value, addr);
 
 	/* Handle pullup/pulldown */
 	if (flags) {
@@ -614,7 +626,12 @@ static int rk3288_pinctrl_set_pins(struct udevice *dev, int banknum, int index,
 			addr = &priv->grf->gpio1_p[banknum - 1][ind];
 		debug("%s: addr=%p, val=%x, shift=%x\n", __func__, addr, val,
 		      shift);
-		rk_clrsetreg(addr, 3 << shift, val << shift);
+
+		/* As above, rk_clrsetreg() cannot be used here. */
+		value = readl(addr);
+		value &= ~(mask << shift);
+		value |= (3 << (shift + 16)) | (val << shift);
+		writel(value, addr);
 	}
 
 	return 0;