[RFC PATCH] ARM: OMAP1: Make OMAP15xx MPUIO based GPIO device optional

[Janusz Krzysztofik]

At least one OMAP15xx based board - Amstrad Delta - makes other use
than simple GPIO of OMAP1 MPUIO port.  Since the port is registered
unconditionally at postcore_initcall as "omap_gpio" platform device,
hence occupied by gpio-omap driver, other device driver has no chance
to request its I/O memory resources successfully and may either fail or
proceed without having those resources reserved.
See commit b027274d2e3a ("mtd: ams-delta: fix request_mem_region()
failure") for details.

Even if it's theoretically possible to perform data I/O on the MPUIO
port with help of gpiod_*_array_*() functions, that additional layer
adds too much overhead for a relatively low powerful OMAP15xx machine.
One possible workaround providing acceptable performance would be to
use GPIO chip callbacks directly but that approach hasn't been
accepted.

Instead of inventing a widely acceptable new API for affected driver to
get efficient access to the port over the gpio-omap driver, make
registration of gpio-omap platform device optional for that port.
Boards are then free to decide if they need it as a GPIO device and can
call its initialization, or can assign the port resources to another
device.

Signed-off-by: Janusz Krzysztofik <jmkrzyszt@xxxxxxxxx>
---
 arch/arm/mach-omap1/board-generic.c   | 2 ++
 arch/arm/mach-omap1/board-innovator.c | 7 ++++++-
 arch/arm/mach-omap1/board-palmte.c    | 2 ++
 arch/arm/mach-omap1/board-palmtt.c    | 2 ++
 arch/arm/mach-omap1/board-palmz71.c   | 2 ++
 arch/arm/mach-omap1/board-sx1.c       | 2 ++
 arch/arm/mach-omap1/common.h          | 3 +++
 arch/arm/mach-omap1/gpio15xx.c        | 6 +++++-
 8 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-omap1/board-generic.c b/arch/arm/mach-omap1/board-generic.c
index 9708629f8c5f..3f812061095e 100644
--- a/arch/arm/mach-omap1/board-generic.c
+++ b/arch/arm/mach-omap1/board-generic.c
@@ -55,6 +55,8 @@ static void __init omap_generic_init(void)
 {
 #ifdef CONFIG_ARCH_OMAP15XX
 	if (cpu_is_omap15xx()) {
+		omap15xx_mpuio_init();
+
 		/* mux pins for uarts */
 		omap_cfg_reg(UART1_TX);
 		omap_cfg_reg(UART1_RTS);
diff --git a/arch/arm/mach-omap1/board-innovator.c b/arch/arm/mach-omap1/board-innovator.c
index 8c286a29f24b..33b74efe3352 100644
--- a/arch/arm/mach-omap1/board-innovator.c
+++ b/arch/arm/mach-omap1/board-innovator.c
@@ -373,8 +373,13 @@ static inline void innovator_mmc_init(void)
 
 static void __init innovator_init(void)
 {
-	if (cpu_is_omap1510())
+#ifdef CONFIG_ARCH_OMAP15XX
+	if (cpu_is_omap1510()) {
+		omap15xx_mpuio_init();
+
 		omap1510_fpga_init_irq();
+	}
+#endif
 	innovator_init_smc91x();
 
 #ifdef CONFIG_ARCH_OMAP15XX
diff --git a/arch/arm/mach-omap1/board-palmte.c b/arch/arm/mach-omap1/board-palmte.c
index 2dc5deb19803..b8620e4a2958 100644
--- a/arch/arm/mach-omap1/board-palmte.c
+++ b/arch/arm/mach-omap1/board-palmte.c
@@ -210,6 +210,8 @@ static void __init palmte_misc_gpio_setup(void)
 
 static void __init omap_palmte_init(void)
 {
+	omap15xx_mpuio_init();
+
 	/* mux pins for uarts */
 	omap_cfg_reg(UART1_TX);
 	omap_cfg_reg(UART1_RTS);
diff --git a/arch/arm/mach-omap1/board-palmtt.c b/arch/arm/mach-omap1/board-palmtt.c
index a23327682df0..20ab494f20c5 100644
--- a/arch/arm/mach-omap1/board-palmtt.c
+++ b/arch/arm/mach-omap1/board-palmtt.c
@@ -256,6 +256,8 @@ static void __init omap_mpu_wdt_mode(int mode) {
 
 static void __init omap_palmtt_init(void)
 {
+	omap15xx_mpuio_init();
+
 	/* mux pins for uarts */
 	omap_cfg_reg(UART1_TX);
 	omap_cfg_reg(UART1_RTS);
diff --git a/arch/arm/mach-omap1/board-palmz71.c b/arch/arm/mach-omap1/board-palmz71.c
index 30b07096197b..5d468111f681 100644
--- a/arch/arm/mach-omap1/board-palmz71.c
+++ b/arch/arm/mach-omap1/board-palmz71.c
@@ -268,6 +268,8 @@ palmz71_gpio_setup(int early)
 static void __init
 omap_palmz71_init(void)
 {
+	omap15xx_mpuio_init();
+
 	/* mux pins for uarts */
 	omap_cfg_reg(UART1_TX);
 	omap_cfg_reg(UART1_RTS);
diff --git a/arch/arm/mach-omap1/board-sx1.c b/arch/arm/mach-omap1/board-sx1.c
index ec27bb3e370f..bbea85943b3b 100644
--- a/arch/arm/mach-omap1/board-sx1.c
+++ b/arch/arm/mach-omap1/board-sx1.c
@@ -311,6 +311,8 @@ static struct platform_device *sx1_devices[] __initdata = {
 
 static void __init omap_sx1_init(void)
 {
+	omap15xx_mpuio_init();
+
 	/* mux pins for uarts */
 	omap_cfg_reg(UART1_TX);
 	omap_cfg_reg(UART1_RTS);
diff --git a/arch/arm/mach-omap1/common.h b/arch/arm/mach-omap1/common.h
index c6537d2c2859..72551c850197 100644
--- a/arch/arm/mach-omap1/common.h
+++ b/arch/arm/mach-omap1/common.h
@@ -95,6 +95,9 @@ static inline int __init omap_32k_timer_init(void)
 }
 #endif
 
+#ifdef CONFIG_ARCH_OMAP15XX
+extern void omap15xx_init_mpuio(void);
+#endif
 #ifdef CONFIG_ARCH_OMAP16XX
 extern int ocpi_enable(void);
 #else
diff --git a/arch/arm/mach-omap1/gpio15xx.c b/arch/arm/mach-omap1/gpio15xx.c
index 312a0924d786..d4c8d257d14d 100644
--- a/arch/arm/mach-omap1/gpio15xx.c
+++ b/arch/arm/mach-omap1/gpio15xx.c
@@ -115,9 +115,13 @@ static int __init omap15xx_gpio_init(void)
 	if (!cpu_is_omap15xx())
 		return -EINVAL;
 
-	platform_device_register(&omap15xx_mpu_gpio);
 	platform_device_register(&omap15xx_gpio);
 
 	return 0;
 }
 postcore_initcall(omap15xx_gpio_init);
+
+void __init omap15xx_mpuio_init(void)
+{
+	platform_device_register(&omap15xx_mpu_gpio);
+}
-- 
2.16.4