[PATCH v1 1/3] gpio: Add APM X-Gene standby GPIO controller driver
From: Y Vo <hidden>
Date: 2014-10-10 03:22:34
Also in:
linux-devicetree, linux-gpio
Dear Arnd, Pls see my answer below: On Thu, Oct 9, 2014 at 7:13 PM, Arnd Bergmann [off-list ref] wrote:
On Thursday 09 October 2014 16:31:18 Y Vo wrote:quoted
Dear Arnd, Thanks a lot for your review. Pls see my answer on blue text below.Please do not send html-encoded email, it will get dropped by all mailing lists.quoted
On Wed, Oct 8, 2014 at 10:13 PM, Arnd Bergmann [off-list ref] wrote:quoted
On Wednesday 08 October 2014 21:52:26 Y Vo wrote:quoted
+ +#define GICD_SPI_BASE 0x78010000You can't hardcode register locations. Please use the proper interfaces to do whatever you want. *APM: We will do that.*quoted
It's probably not ok to map any GIC registers into the GPIO driver, it should operate as a nested irqchip.*APM: We will find the solution, the problem is we want to read the status of that GPIO in case it is configured IRQ. In this case we must access to GIC to read the true value.*Can you explain what the hardware does here? Do you mean you have no way to read the GPIO level from the GPIO controller for any pin that is configured as an interrupt? Can you route all GPIO pins to arbitrary upstream IRQ lines, or is this hardwired in the GPIO block?
APM: There are 6 GPIOs which can support IRQ, they are fixed to use external IRQ from XGIC. (The XGIC is based on the ARM Generic Interrupt Controller Architecture Specification, Architecture version 2.0, The XGIC provides the mechanism to collect interrupt requests (IRQs) from both on-chip as well as off-chip sources and deliver them to the multiple X-Gene1 cores within the X-Gene1 processor), So there are no way to read the GPIO DS when configure as an interrupt. They are specific GPIO for boot another boot chip in X-Gene which can access when boot up. So this is hardwire in the GPIO block. GPIO_DS8 ---> External IRQ0 (XGIC40) GPIO_DS9 ---> External IRQ1 (XGIC41) ... GPIO_DS13 ---> External IRQ5(XGIC45)
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