[PATCH v2 0/3] powerpc: 512x: Convert ADS7845 touchscreen on PDM360NG to device tree

[PATCH v2 0/3] powerpc: 512x: Convert ADS7845 touchscreen on PDM360NG to device tree

[Dmitry Torokhov]

The reason for this series is to remove support for platform data in the
ads7846 touchscreen driver, as pdm360ng is the last user of legacy
platform data in the kernel for this driver.

This series converts the ADS7845 touchscreen on the PDM360NG board to use
Device Tree bindings instead of legacy platform data callbacks:

- Move GPIO controller capabilities into mpc5121.dtsi so all MPC5121
  boards inherit proper controller definitions, and remove redundant
  local declarations from ac14xx.dts

- Update pdm360ng.dts to use "ti,ads7845" with pendown-gpio and
  interrupt-parent referencing gpio_pic

- Add "ifm,pdm360ng" to mpc512x_generic.c and delete obsolete
  pdm360ng.c.

This change has been discussed in '24 but I just got around to
implementing this:

https://lore.kernel.org/r/ZoNHLjmSvCN12vU5@google.com/

Note that this should compile but I have not tried this on real
hardware.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
Changes in v2:
- Set pendown-gpio to GPIO_ACTIVE_LOW in pdm360ng.dts to match the
  active-low hardware pen-down signal
- Expanded commit description of patch 2 explaining why early boot setup
  in pdm360ng_penirq_init() is harmless prior to patch 3
- Removed Anatolij Gustschin since I got a bounce telling he's no longer
  with DENX
- Link to v1: https://lore.kernel.org/r/20260718-ads7846-pdm360ng-v1-0-f318f85cda57@gmail.com

---
Dmitry Torokhov (3):
      powerpc/dts: mpc5121: Move GPIO controller properties to SoC dtsi
      powerpc/dts: pdm360ng: Convert ADS7845 touchscreen to DT bindings
      powerpc/512x: Remove pdm360ng platform setup in favor of mpc512x_generic

 arch/powerpc/boot/dts/ac14xx.dts              |  13 ---
 arch/powerpc/boot/dts/mpc5121.dtsi            |   6 +-
 arch/powerpc/boot/dts/pdm360ng.dts            |   8 +-
 arch/powerpc/platforms/512x/Kconfig           |   3 +-
 arch/powerpc/platforms/512x/Makefile          |   1 -
 arch/powerpc/platforms/512x/mpc512x_generic.c |   1 +
 arch/powerpc/platforms/512x/pdm360ng.c        | 126 --------------------------
 7 files changed, 13 insertions(+), 145 deletions(-)
---
base-commit: 8e9685d3c41c35dd1b37df70d854137abcb2fbac
change-id: 20260717-ads7846-pdm360ng-ec7ed9f72f82

Thanks.

-- 
Dmitry

[PATCH v2 1/3] powerpc/dts: mpc5121: Move GPIO controller properties to SoC dtsi

[Dmitry Torokhov]

Define gpio@1100 with label gpio_pic as a GPIO controller and
interrupt controller directly in mpc5121.dtsi so all MPC5121 boards
inherit the correct controller capabilities.

Remove the redundant local controller property declaration block from
ac14xx.dts.

Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 arch/powerpc/boot/dts/ac14xx.dts   | 13 -------------
 arch/powerpc/boot/dts/mpc5121.dtsi |  6 +++++-
 2 files changed, 5 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/boot/dts/ac14xx.dts b/arch/powerpc/boot/dts/ac14xx.dts
index 5d8877e1f4ad..05fcf08df1ca 100644
--- a/arch/powerpc/boot/dts/ac14xx.dts
+++ b/arch/powerpc/boot/dts/ac14xx.dts
@@ -148,19 +148,6 @@ clock@f00 {
 			compatible = "fsl,mpc5121rev2-clock", "fsl,mpc5121-clock";
 		};
 
-		/*
-		 * GPIO PIC:
-		 * interrupts cell = <pin nr, sense>
-		 * sense == 8: Level, low assertion
-		 * sense == 2: Edge, high-to-low change
-		 */
-		gpio_pic: gpio@1100 {
-			gpio-controller;
-			#gpio-cells = <2>;
-			interrupt-controller;
-			#interrupt-cells = <2>;
-		};
-
 		sdhc@1500 {
 			cd-gpios = <&gpio_pic 23 0>;	/* card detect */
 			wp-gpios = <&gpio_pic 24 0>;	/* write protect */
diff --git a/arch/powerpc/boot/dts/mpc5121.dtsi b/arch/powerpc/boot/dts/mpc5121.dtsi
index a278fb7b9e71..9c5dacb94b92 100644
--- a/arch/powerpc/boot/dts/mpc5121.dtsi
+++ b/arch/powerpc/boot/dts/mpc5121.dtsi
@@ -146,10 +146,14 @@ pmc@1000 {
 			interrupts = <83 0x8>;
 		};
 
-		gpio@1100 {
+		gpio_pic: gpio@1100 {
 			compatible = "fsl,mpc5121-gpio";
 			reg = <0x1100 0x100>;
 			interrupts = <78 0x8>;
+			gpio-controller;
+			#gpio-cells = <2>;
+			interrupt-controller;
+			#interrupt-cells = <2>;
 		};
 
 		can@1300 {

-- 
2.55.0.229.g6434b31f56-goog

[PATCH v2 2/3] powerpc/dts: pdm360ng: Convert ADS7845 touchscreen to DT bindings

[Dmitry Torokhov]

The PDM360NG board is equipped with an ADS7845 touchscreen controller.
Previously, pdm360ng.dts used "ti,ads7846" as a placeholder and relied
on platform data in pdm360ng.c to override the model to 7845.

Update the ts@0 touchscreen node in pdm360ng.dts to use the correct
"ti,ads7845" compatible string along with pendown-gpio (using
GPIO_ACTIVE_LOW) and interrupt-parent properties referencing gpio_pic.

Note that changing the compatible string to "ti,ads7845" causes the
legacy platform data notifier in pdm360ng.c to skip injecting platform
data, allowing ads7846 to parse DT properties natively. Although
pdm360ng_penirq_init() in pdm360ng.c still runs on boot prior to removing
pdm360ng.c, its direct GPIO register writes are harmless because the
gpio-mpc8xxx driver resets and re-unmasks pin 25 on demand when the
ads7846 driver requests its interrupt.

Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 arch/powerpc/boot/dts/pdm360ng.dts | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/boot/dts/pdm360ng.dts b/arch/powerpc/boot/dts/pdm360ng.dts
index 67c3b9db75d7..05e93ca294ee 100644
--- a/arch/powerpc/boot/dts/pdm360ng.dts
+++ b/arch/powerpc/boot/dts/pdm360ng.dts
@@ -9,6 +9,7 @@
  * Copyright 2008 Freescale Semiconductor Inc.
  */
 
+#include <dt-bindings/gpio/gpio.h>
 #include "mpc5121.dtsi"
 
 / {
@@ -176,11 +177,12 @@ psc@11900 {
 
 			/* ADS7845 touch screen controller */
 			ts@0 {
-				compatible = "ti,ads7846";
+				compatible = "ti,ads7845";
 				reg = <0x0>;
 				spi-max-frequency = <3000000>;
-				/* pen irq is GPIO25 */
-				interrupts = <78 0x8>;
+				interrupt-parent = <&gpio_pic>;
+				interrupts = <25 0x8>;
+				pendown-gpio = <&gpio_pic 25 GPIO_ACTIVE_LOW>;
 			};
 		};
 

-- 
2.55.0.229.g6434b31f56-goog

[PATCH v2 3/3] powerpc/512x: Remove pdm360ng platform setup in favor of mpc512x_generic

[Dmitry Torokhov]

Now that the ADS7845 touchscreen on PDM360NG is fully described in the
device tree, custom platform setup in pdm360ng.c is no longer needed.

Add ifm,pdm360ng to the board match list in mpc512x_generic.c, update
Kconfig to select MPC512x_GENERIC for PDM360NG, and remove pdm360ng.c.

Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 arch/powerpc/platforms/512x/Kconfig           |   3 +-
 arch/powerpc/platforms/512x/Makefile          |   1 -
 arch/powerpc/platforms/512x/mpc512x_generic.c |   1 +
 arch/powerpc/platforms/512x/pdm360ng.c        | 126 --------------------------
 4 files changed, 3 insertions(+), 128 deletions(-)

diff --git a/arch/powerpc/platforms/512x/Kconfig b/arch/powerpc/platforms/512x/Kconfig
index deecede78776..9d46d791af05 100644
--- a/arch/powerpc/platforms/512x/Kconfig
+++ b/arch/powerpc/platforms/512x/Kconfig
@@ -32,11 +32,12 @@ config MPC512x_GENERIC
 	  which do not need custom platform specific setup.
 
 	  Compatible boards include:  Protonic LVT base boards (ZANMCU
-	  and VICVT2), Freescale MPC5125 Tower system.
+	  and VICVT2), Freescale MPC5125 Tower system, IFM PDM360NG.
 
 config PDM360NG
 	bool "ifm PDM360NG board"
 	depends on PPC_MPC512x
+	select MPC512x_GENERIC
 	select DEFAULT_UIMAGE
 	help
 	  This option enables support for the PDM360NG board.
diff --git a/arch/powerpc/platforms/512x/Makefile b/arch/powerpc/platforms/512x/Makefile
index 2daf22ee26a0..4da6f6923d8f 100644
--- a/arch/powerpc/platforms/512x/Makefile
+++ b/arch/powerpc/platforms/512x/Makefile
@@ -7,4 +7,3 @@ obj-y				+= mpc512x_shared.o
 obj-$(CONFIG_MPC5121_ADS)	+= mpc5121_ads.o mpc5121_ads_cpld.o
 obj-$(CONFIG_MPC512x_GENERIC)	+= mpc512x_generic.o
 obj-$(CONFIG_MPC512x_LPBFIFO)	+= mpc512x_lpbfifo.o
-obj-$(CONFIG_PDM360NG)		+= pdm360ng.o
diff --git a/arch/powerpc/platforms/512x/mpc512x_generic.c b/arch/powerpc/platforms/512x/mpc512x_generic.c
index d4fa6c302ccf..d330d3d85887 100644
--- a/arch/powerpc/platforms/512x/mpc512x_generic.c
+++ b/arch/powerpc/platforms/512x/mpc512x_generic.c
@@ -24,6 +24,7 @@ static const char * const board[] __initconst = {
 	"prt,prtlvt",
 	"fsl,mpc5125ads",
 	"ifm,ac14xx",
+	"ifm,pdm360ng",
 	NULL
 };
 
diff --git a/arch/powerpc/platforms/512x/pdm360ng.c b/arch/powerpc/platforms/512x/pdm360ng.c
deleted file mode 100644
index 8bbbf78bb42b..000000000000
--- a/arch/powerpc/platforms/512x/pdm360ng.c
+++ /dev/null
@@ -1,126 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * Copyright (C) 2010 DENX Software Engineering
- *
- * Anatolij Gustschin, <agust@denx.de>
- *
- * PDM360NG board setup
- */
-
-#include <linux/device.h>
-#include <linux/kernel.h>
-#include <linux/io.h>
-#include <linux/of.h>
-#include <linux/of_address.h>
-#include <linux/of_fdt.h>
-
-#include <asm/machdep.h>
-#include <asm/ipic.h>
-
-#include "mpc512x.h"
-
-#if defined(CONFIG_TOUCHSCREEN_ADS7846) || \
-    defined(CONFIG_TOUCHSCREEN_ADS7846_MODULE)
-#include <linux/interrupt.h>
-#include <linux/spi/ads7846.h>
-#include <linux/spi/spi.h>
-#include <linux/notifier.h>
-
-static void *pdm360ng_gpio_base;
-
-static int pdm360ng_get_pendown_state(void)
-{
-	u32 reg;
-
-	reg = in_be32(pdm360ng_gpio_base + 0xc);
-	if (reg & 0x40)
-		setbits32(pdm360ng_gpio_base + 0xc, 0x40);
-
-	reg = in_be32(pdm360ng_gpio_base + 0x8);
-
-	/* return 1 if pen is down */
-	return (reg & 0x40) == 0;
-}
-
-static struct ads7846_platform_data pdm360ng_ads7846_pdata = {
-	.model			= 7845,
-	.get_pendown_state	= pdm360ng_get_pendown_state,
-	.irq_flags		= IRQF_TRIGGER_LOW,
-};
-
-static int __init pdm360ng_penirq_init(void)
-{
-	struct device_node *np;
-
-	np = of_find_compatible_node(NULL, NULL, "fsl,mpc5121-gpio");
-	if (!np) {
-		pr_err("%s: Can't find 'mpc5121-gpio' node\n", __func__);
-		return -ENODEV;
-	}
-
-	pdm360ng_gpio_base = of_iomap(np, 0);
-	of_node_put(np);
-	if (!pdm360ng_gpio_base) {
-		pr_err("%s: Can't map gpio regs.\n", __func__);
-		return -ENODEV;
-	}
-	out_be32(pdm360ng_gpio_base + 0xc, 0xffffffff);
-	setbits32(pdm360ng_gpio_base + 0x18, 0x2000);
-	setbits32(pdm360ng_gpio_base + 0x10, 0x40);
-
-	return 0;
-}
-
-static int pdm360ng_touchscreen_notifier_call(struct notifier_block *nb,
-					unsigned long event, void *__dev)
-{
-	struct device *dev = __dev;
-
-	if ((event == BUS_NOTIFY_ADD_DEVICE) &&
-	    of_device_is_compatible(dev->of_node, "ti,ads7846")) {
-		dev->platform_data = &pdm360ng_ads7846_pdata;
-		return NOTIFY_OK;
-	}
-	return NOTIFY_DONE;
-}
-
-static struct notifier_block pdm360ng_touchscreen_nb = {
-	.notifier_call = pdm360ng_touchscreen_notifier_call,
-};
-
-static void __init pdm360ng_touchscreen_init(void)
-{
-	if (pdm360ng_penirq_init())
-		return;
-
-	bus_register_notifier(&spi_bus_type, &pdm360ng_touchscreen_nb);
-}
-#else
-static inline void __init pdm360ng_touchscreen_init(void)
-{
-}
-#endif /* CONFIG_TOUCHSCREEN_ADS7846 */
-
-static void __init pdm360ng_init(void)
-{
-	mpc512x_init();
-	pdm360ng_touchscreen_init();
-}
-
-static int __init pdm360ng_probe(void)
-{
-	mpc512x_init_early();
-
-	return 1;
-}
-
-define_machine(pdm360ng) {
-	.name			= "PDM360NG",
-	.compatible		= "ifm,pdm360ng",
-	.probe			= pdm360ng_probe,
-	.setup_arch		= mpc512x_setup_arch,
-	.init			= pdm360ng_init,
-	.init_IRQ		= mpc512x_init_IRQ,
-	.get_irq		= ipic_get_irq,
-	.restart		= mpc512x_restart,
-};

-- 
2.55.0.229.g6434b31f56-goog

Re: [PATCH v2 2/3] powerpc/dts: pdm360ng: Convert ADS7845 touchscreen to DT bindings

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Unchecked Error Return / Uninitialized Memory in ads7846_setup_spi_msg
--

--- Patch [2]: [PATCH v2 2/3] powerpc/dts: pdm360ng: Convert ADS7845 touchscreen to DT bindings ---
commit 06fbaa99ffa69ed22e692eeb23d6d33c9a3cdfdd
Author: Dmitry Torokhov <dmitry.torokhov@gmail.com>

powerpc/dts: pdm360ng: Convert ADS7845 touchscreen to DT bindings

This commit updates the pdm360ng device tree to use the correct "ti,ads7845"
compatible string and native DT properties for the touchscreen. It removes the
reliance on legacy platform data injection for configuring the device.

> diff --git a/arch/powerpc/boot/dts/pdm360ng.dts b/arch/powerpc/boot/dts/pdm360ng.dts
> index 67c3b9db75d76..05e93ca294ee3 100644
> --- a/arch/powerpc/boot/dts/pdm360ng.dts
> +++ b/arch/powerpc/boot/dts/pdm360ng.dts
[ ... ]
> @@ -176,11 +177,12 @@ psc@11900 {
>  
>  			/* ADS7845 touch screen controller */
>  			ts@0 {
> -				compatible = "ti,ads7846";
> +				compatible = "ti,ads7845";
[ ... ]

While reviewing the touchscreen configuration changes, I noticed a detail in
the underlying driver's probe function:

drivers/input/touchscreen/ads7846.c:ads7846_probe() {
	...
	ads7846_setup_spi_msg(ts, pdata);

	ts->reg = devm_regulator_get(dev, "vcc");
	...
}

[Severity: High]
This is a pre-existing issue, but does this code ignore the return value of
ads7846_setup_spi_msg()?

If memory allocation inside ads7846_setup_spi_msg() fails, it returns
-ENOMEM, but spi_message_init() would be skipped. 

If probe continues and eventually calls ads7846_read_state(), it passes the
uninitialized ts->msg array to spi_sync(). Because the transfers list head
has NULL next and prev pointers in this scenario, could this result in an
immediate NULL pointer dereference inside the SPI core?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260719-ads7846-pdm360ng-v2-0-1198bd108502@gmail.com?part=2