diff options
| author | Stefan Agner <stefan.agner@toradex.com> | 2016-11-23 16:14:23 -0800 |
|---|---|---|
| committer | Marcel Ziswiler <marcel.ziswiler@toradex.com> | 2018-12-09 23:11:12 +0100 |
| commit | 6c0549c5697f6edf02cb01d1f2ddff3a7031960b (patch) | |
| tree | bcbb0fa493ba07c64fe553b04018ef4e83914a3a /drivers | |
| parent | bdbe4d90a550a09cfe3973fdbf0cbd1670c2e3a9 (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)
Diffstat (limited to 'drivers')
| -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 c1a1e00b8cb0..b7bc18b630ba 100644 --- a/drivers/gpio/gpio-mxc.c +++ b/drivers/gpio/gpio-mxc.c @@ -20,6 +20,7 @@ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ +#include <linux/moduleparam.h> #include <linux/err.h> #include <linux/init.h> #include <linux/interrupt.h> @@ -36,6 +37,10 @@ #include <linux/of_device.h> #include <linux/bug.h> +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 */ @@ -429,8 +434,10 @@ static int mxc_gpio_probe(struct platform_device *pdev) return port->irq; /* 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) { /* |