pinctrl: mediatek: Free eint data on failure

The pinctrl driver can work without the EINT resource, but, if it is
expected to have this resource but the mtk_build_eint() function fails
after allocating their data (because can't get the resource or can't map
the irq), the data is not freed and you end with a NULL pointer
dereference. Fix this by freeing the data if mtk_build_eint() fails, so
pinctrl still works and doesn't hang.

This is noticeable after commit f97dbf48 ("irqchip/mtk-sysirq: Convert
to a platform driver") on MT8183 because, due this commit, the pinctrl driver
fails to map the irq and spots the following bug:

[    1.947597] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004
[    1.956404] Mem abort info:
[    1.959203]   ESR = 0x96000004
[    1.962259]   EC = 0x25: DABT (current EL), IL = 32 bits
[    1.967565]   SET = 0, FnV = 0
[    1.970613]   EA = 0, S1PTW = 0
[    1.973747] Data abort info:
[    1.976619]   ISV = 0, ISS = 0x00000004
[    1.980447]   CM = 0, WnR = 0
[    1.983410] [0000000000000004] user address but active_mm is swapper
[    1.989759] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[    1.995322] Modules linked in:
[    1.998371] CPU: 7 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc1+ #44
[    2.004715] Hardware name: MediaTek krane sku176 board (DT)
[    2.010280] pstate: 60000005 (nZCv daif -PAN -UAO BTYPE=--)
[    2.015850] pc : mtk_eint_set_debounce+0x48/0x1b8
[    2.020546] lr : mtk_eint_set_debounce+0x34/0x1b8
[    2.025239] sp : ffff80001008baa0
[    2.028544] x29: ffff80001008baa0 x28: ffff0000ff7ff790
[    2.033847] x27: ffff0000f9ec34b0 x26: ffff0000f9ec3480
[    2.039150] x25: ffff0000fa576410 x24: ffff0000fa502800
[    2.044453] x23: 0000000000001388 x22: ffff0000fa635f80
[    2.049755] x21: 0000000000000008 x20: 0000000000000000
[    2.055058] x19: 0000000000000071 x18: 0000000000000001
[    2.060360] x17: 0000000000000000 x16: 0000000000000000
[    2.065662] x15: ffff0000facc8470 x14: ffffffffffffffff
[    2.070965] x13: 0000000000000001 x12: 00000000000000c0
[    2.076267] x11: 0000000000000040 x10: 0000000000000070
[    2.081569] x9 : ffffaec0063d24d8 x8 : ffff0000fa800270
[    2.086872] x7 : 0000000000000000 x6 : 0000000000000011
[    2.092174] x5 : ffff0000fa800248 x4 : ffff0000fa800270
[    2.097476] x3 : ffff8000100c5000 x2 : 0000000000000000
[    2.102778] x1 : 0000000000000000 x0 : 0000000000000000
[    2.108081] Call trace:
[    2.110520]  mtk_eint_set_debounce+0x48/0x1b8
[    2.114870]  mtk_gpio_set_config+0x5c/0x78
[    2.118958]  gpiod_set_config+0x5c/0x78
[    2.122786]  gpiod_set_debounce+0x18/0x28
[    2.126789]  gpio_keys_probe+0x50c/0x910
[    2.130705]  platform_drv_probe+0x54/0xa8
[    2.134705]  really_probe+0xe4/0x3b0
[    2.138271]  driver_probe_device+0x58/0xb8
[    2.142358]  device_driver_attach+0x74/0x80
[    2.146532]  __driver_attach+0x58/0xe0
[    2.150274]  bus_for_each_dev+0x70/0xc0
[    2.154100]  driver_attach+0x24/0x30
[    2.157666]  bus_add_driver+0x14c/0x1f0
[    2.161493]  driver_register+0x64/0x120
[    2.165319]  __platform_driver_register+0x48/0x58
[    2.170017]  gpio_keys_init+0x1c/0x28
[    2.173672]  do_one_initcall+0x54/0x1b4
[    2.177499]  kernel_init_freeable+0x1d0/0x238
[    2.181848]  kernel_init+0x14/0x118
[    2.185328]  ret_from_fork+0x10/0x34
[    2.188899] Code: a9438ac1 12001266 f94006c3 121e766a (b9400421)
[    2.194991] ---[ end trace 168cf7b3324b6570 ]---
[    2.199611] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[    2.207260] SMP: stopping secondary CPUs
[    2.211294] Kernel Offset: 0x2ebff4800000 from 0xffff800010000000
[    2.217377] PHYS_OFFSET: 0xffffb50500000000
[    2.221551] CPU features: 0x0240002,2188200c
[    2.225811] Memory Limit: none
[    2.228860] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]---

Fixes: 89132dd8 ("pinctrl: mediatek: extend eint build to pinctrl-mtk-common-v2.c")
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Acked-by: Sean Wang <sean.wang@kernel.org>
Link: https://lore.kernel.org/r/20201001142511.3560143-1-enric.balletbo@collabora.com
[rebased on changed infrastructure]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/mediatek/pinctrl-mtk-common-v2.c

@@ -354,6 +354,7 @@ static const struct mtk_eint_xt mtk_eint_xt = {
 int mtk_build_eint(struct mtk_pinctrl *hw, struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
+	int ret;
 
 	if (!IS_ENABLED(CONFIG_EINT_MTK))
 		return 0;
@@ -366,15 +367,21 @@ int mtk_build_eint(struct mtk_pinctrl *hw, struct platform_device *pdev)
 		return -ENOMEM;
 
 	hw->eint->base = devm_platform_ioremap_resource_byname(pdev, "eint");
-	if (IS_ERR(hw->eint->base))
-		return PTR_ERR(hw->eint->base);
+	if (IS_ERR(hw->eint->base)) {
+		ret = PTR_ERR(hw->eint->base);
+		goto err_free_eint;
+	}
 
 	hw->eint->irq = irq_of_parse_and_map(np, 0);
-	if (!hw->eint->irq)
-		return -EINVAL;
+	if (!hw->eint->irq) {
+		ret = -EINVAL;
+		goto err_free_eint;
+	}
 
-	if (!hw->soc->eint_hw)
-		return -ENODEV;
+	if (!hw->soc->eint_hw) {
+		ret = -ENODEV;
+		goto err_free_eint;
+	}
 
 	hw->eint->dev = &pdev->dev;
 	hw->eint->hw = hw->soc->eint_hw;
@@ -382,6 +389,11 @@ int mtk_build_eint(struct mtk_pinctrl *hw, struct platform_device *pdev)
 	hw->eint->gpio_xlate = &mtk_eint_xt;
 
 	return mtk_eint_do_init(hw->eint);
+
+err_free_eint:
+	devm_kfree(hw->dev, hw->eint);
+	hw->eint = NULL;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(mtk_build_eint);