By taking parts of the programming handshaking protocol on faith it is
possible to make due with only two GPIO for programming Altera
FPGAs. This is not a very advisable practice, but sometime unavoidable
in GPIO constrained designs.
Signed-off-by: Andrey Smirnov <andrew.smir...@gmail.com>
---
drivers/firmware/altera_serial.c | 59 ++++++++++++++++++++++++++++++----------
1 file changed, 44 insertions(+), 15 deletions(-)
diff --git a/drivers/firmware/altera_serial.c b/drivers/firmware/altera_serial.c
index c5ffbb6..4527d27 100644
--- a/drivers/firmware/altera_serial.c
+++ b/drivers/firmware/altera_serial.c
@@ -25,6 +25,7 @@
#include <fcntl.h>
#include <fs.h>
+
/*
* Physical requirements:
* - three free GPIOs for the signals nCONFIG, CONFIGURE_DONE, nSTATUS
@@ -67,13 +68,19 @@ static int altera_spi_open(struct firmware_handler *fh)
* after about 2 µs the FPGA must acknowledge with
* STATUS and CONFIG DONE lines at low level
*/
- ret = wait_on_timeout(2 * USECOND,
+ if (gpio_is_valid(this->nstat_gpio)) {
+ ret = wait_on_timeout(2 * USECOND,
(gpio_get_value(this->nstat_gpio) == 0) &&
(gpio_get_value(this->confd_gpio) == 0));
+ } else {
+ ret = wait_on_timeout(2 * USECOND,
+ (gpio_get_value(this->confd_gpio) == 0));
+ }
+
if (ret != 0) {
dev_err(dev, "FPGA does not acknowledge the programming
initiation\n");
- if (gpio_get_value(this->nstat_gpio))
+ if (gpio_is_valid(this->nstat_gpio) &&
gpio_get_value(this->nstat_gpio))
dev_err(dev, "STATUS is still high!\n");
if (gpio_get_value(this->confd_gpio))
dev_err(dev, "CONFIG DONE is still high!\n");
@@ -90,11 +97,16 @@ static int altera_spi_open(struct firmware_handler *fh)
* after about 1506 µs the FPGA must acknowledge this step
* with the STATUS line at high level
*/
- ret = wait_on_timeout(1600 * USECOND,
+
+ if (gpio_is_valid(this->nstat_gpio)) {
+ ret = wait_on_timeout(1600 * USECOND,
gpio_get_value(this->nstat_gpio) == 1);
- if (ret != 0) {
- dev_err(dev, "FPGA does not acknowledge the programming
start\n");
- return ret;
+ if (ret != 0) {
+ dev_err(dev, "FPGA does not acknowledge the programming
start\n");
+ return ret;
+ }
+ } else {
+ udelay(1600);
}
dev_dbg(dev, "Initiating passed\n");
@@ -177,16 +189,24 @@ static int altera_spi_close(struct firmware_handler *fh)
* when programming was successful,
* both status lines should be at high level
*/
- ret = wait_on_timeout(10 * USECOND,
+ if (gpio_is_valid(this->nstat_gpio)) {
+ ret = wait_on_timeout(10 * USECOND,
(gpio_get_value(this->nstat_gpio) == 1) &&
(gpio_get_value(this->confd_gpio) == 1));
+ } else {
+ ret = wait_on_timeout(10 * USECOND,
+ (gpio_get_value(this->confd_gpio) == 1));
+
+ }
+
if (ret == 0) {
dev_dbg(dev, "Programming successful\n");
return ret;
}
dev_err(dev, "Programming failed due to time out\n");
- if (gpio_get_value(this->nstat_gpio) == 0)
+ if (gpio_is_valid(this->nstat_gpio) &&
+ gpio_get_value(this->nstat_gpio) == 0)
dev_err(dev, "STATUS is still low!\n");
if (gpio_get_value(this->confd_gpio) == 0)
dev_err(dev, "CONFIG DONE is still low!\n");
@@ -201,10 +221,15 @@ static int altera_spi_of(struct device_d *dev, struct
fpga_spi *this)
int ret;
name = "nstat-gpio";
- this->nstat_gpio = of_get_named_gpio(n, name, 0);
- if (this->nstat_gpio < 0) {
- ret = this->nstat_gpio;
- goto out;
+ if (!of_get_property(n, name, NULL)) {
+ dev_info(dev, "nstat-gpio is not specified, assuming it is not
connected\n");
+ this->nstat_gpio = -1;
+ } else {
+ this->nstat_gpio = of_get_named_gpio(n, name, 0);
+ if (this->nstat_gpio < 0) {
+ ret = this->nstat_gpio;
+ goto out;
+ }
}
name = "confd-gpio";
@@ -225,9 +250,13 @@ static int altera_spi_of(struct device_d *dev, struct
fpga_spi *this)
ret = gpio_direction_output(this->nconfig_gpio, 1);
if (ret)
return ret;
- ret = gpio_direction_input(this->nstat_gpio);
- if (ret)
- return ret;
+
+ if (gpio_is_valid(this->nstat_gpio)) {
+ ret = gpio_direction_input(this->nstat_gpio);
+ if (ret)
+ return ret;
+ }
+
ret = gpio_direction_input(this->confd_gpio);
if (ret)
return ret;
--
2.1.0
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