ppc4xx: Add functionality to GPIO support
This patch makes two additions to GPIO support:
First, it adds function gpio_read_in_bit() to read the a bit from the
GPIO Input Register (GPIOx_IR) in the same way that function
gpio_read_out_bit() reads a bit from the GPIO Output Register
(GPIOx_OR).
Second, it modifies function gpio_set_chip_configuration() to provide
an additional option for configuring the GPIO from the
"CFG_4xx_GPIO_TABLE".
According to the 440EPx User's Manual, when an alternate output is used,
the three-state control is configured in one of two ways, depending on
the particular output. The first option is to select the corresponding
alternate three-state control in the GPIOx_TRSH/L registers. The second
option is to select the GPIO Three-State Control Register (GPIOx_TCR) in
the GPIOx_TRSH/L registers, and set the corresponding bit in the
GPIOx_TCR register to enable the output. For example, the Manual
specifies configuring the GPIO00 Alternate 1 Signal (PreAddr07) to use
the alternate three-state control (first option), and specifies
configuring the GPIO32 Alternate 1 Signal (USB2OM0) with the output
enabled in the GPIOx_TCR register (second option).
Currently, gpio_set_chip_configuration() configures all alternate signal
outputs to use the first option. This patch allow the second option to
be selected by setting the "out_val" element in the table entry to
"GPIO_OUT_1". The first option is used when the "out_val" element is
set to "GPIO_OUT_0". Because "out_val" is not currently used when an
alternate signal is selected, and because all current GPIO tables set
"out_val" to "GPIO_OUT_0" for all alternate signals, this patch should
not change any existing configurations.
Signed-off-by: Larry Johnson <lrj@acm.org>
diff --git a/include/asm-ppc/gpio.h b/include/asm-ppc/gpio.h
index d0c3eba..c3a4a88 100644
--- a/include/asm-ppc/gpio.h
+++ b/include/asm-ppc/gpio.h
@@ -88,6 +88,7 @@
void gpio_config(int pin, int in_out, int gpio_alt, int out_val);
void gpio_write_bit(int pin, int val);
int gpio_read_out_bit(int pin);
+int gpio_read_in_bit(int pin);
void gpio_set_chip_configuration(void);
#endif /* __ASM_PPC_GPIO_H */