diff options
| author | Stefan Agner <stefan.agner@toradex.com> | 2016-11-23 16:14:23 -0800 |
|---|---|---|
| committer | Oleksandr Suvorov <oleksandr.suvorov@toradex.com> | 2021-01-27 11:03:27 +0200 |
| commit | b4afeb8e4f41948b83d0b32653b1ad56611e5cf9 (patch) | |
| tree | 78ecee95c45fa2fc944dda03e9253dab955c1408 /drivers/gpio | |
| parent | 955712697c7fdfb4702421b88d676cde0d42c284 (diff) | |
gpio: mxc: clear interrupt mask/status optionally
Add a kernel parameter ("gpio-mxc.noclearirq") to disable
unconditional interrupt mask/clearing. This is useful when a
second CPU (the Cortex-M4) is accessing the same GPIO bank.
Using the same GPIO bank from the Cortex-A7 and M4 sounds risky,
but it seems to work quite well. Most registers are write only
(e.g. interrupt status register can be cleared with a single
write), which makes them safe for concurrent access. However,
sharing a single GPIO bank between two cores does not allow to
use the Resource Domain Controller. Hence for secure applications
assigning a dedicated GPIO bank is still preferable.
Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
Acked-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
(cherry picked from commit 4cfa939c693b20ca213f054c1dfe5583d966beb4)
(cherry picked from commit 6fe2ede9d83fee52703dc3403aa0a2cf29704595)
Diffstat (limited to 'drivers/gpio')
| -rw-r--r-- | drivers/gpio/gpio-mxc.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/gpio/gpio-mxc.c b/drivers/gpio/gpio-mxc.c index 0185b6e57e78..5a2cf486a686 100644 --- a/drivers/gpio/gpio-mxc.c +++ b/drivers/gpio/gpio-mxc.c @@ -7,6 +7,7 @@ // Authors: Daniel Mack, Juergen Beisert. // Copyright (C) 2004-2010 Freescale Semiconductor, Inc. All Rights Reserved. +#include <linux/moduleparam.h> #include <linux/clk.h> #include <linux/err.h> #include <linux/init.h> @@ -33,6 +34,10 @@ #define IMX_SC_IRQ_PAD (1 << 1) #endif +static bool noclearirq = false; +module_param(noclearirq, bool, 0); +MODULE_PARM_DESC(noclearirq, "do not clear IRQ mask/status on probe"); + enum mxc_gpio_hwtype { IMX1_GPIO, /* runs on i.mx1 */ IMX21_GPIO, /* runs on i.mx21 and i.mx27 */ @@ -671,8 +676,10 @@ static int mxc_gpio_probe(struct platform_device *pdev) goto out_pm_dis; /* disable the interrupt and clear the status */ - writel(0, port->base + GPIO_IMR); - writel(~0, port->base + GPIO_ISR); + if (!noclearirq) { + writel(0, port->base + GPIO_IMR); + writel(~0, port->base + GPIO_ISR); + } if (mxc_gpio_hwtype == IMX21_GPIO) { /* |