Add code to control the PA of the SOB-BTSlaforge/sob-bts-pa-ctrl

At least in v1 of the SOB-BTS, there is a SX1502 I2C GPIO expander
to control the two different PAs in the system.  This adds a SX150x
driver on top of Linux userspae i2c-dev access, and a thin layer of API
functions as well as a command line tool.

The code is currently still untested.

1 files changed, 73 insertions, 0 deletions

diff --git a/src/osmo-bts-sysmo/misc/sob_bts_pa.c b/src/osmo-bts-sysmo/misc/sob_bts_pa.c
new file mode 100644
index 00000000..24240884
--- /dev/null
+++ b/src/osmo-bts-sysmo/misc/sob_bts_pa.c
@@ -0,0 +1,73 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <errno.h>
+#include <limits.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#include "i2c-dev.h"
+#include "sx150x.h"
+
+#define SOB_BTS_NUM_PA	2
+
+static int g_pa_gpio_offset;
+static int g_i2c_fd;
+
+int sob_bts_pa_enable(int pa_num, int enable)
+{
+	int level;
+
+	if (pa_num >= SOB_BTS_NUM_PA)
+		return -EINVAL;
+
+	if (enable)
+		level = 0;
+	else
+		level = 1;
+
+	return sx150x_gpio_set(g_i2c_fd, g_pa_gpio_offset + pa_num, level);
+}
+
+int sob_bts_pa_init(int adapter_nr)
+{
+	char filename[PATH_MAX];
+	int rc;
+
+	snprintf(filename, sizeof(filename)-1, "/dev/i2c-%d", adapter_nr);
+	rc = open(filename, O_RDWR);
+	if (rc < 0) {
+		fprintf(stderr, "Error opening the device: %d\n", rc);
+		return rc;
+	}
+
+	g_i2c_fd = rc;
+
+	rc = ioctl(g_i2c_fd, I2C_SLAVE, SX150x_ADDR_ADDR0);
+	if (rc < 0) {
+		fprintf(stderr, "Error setting slave addr: %d\n", rc);
+		close(g_i2c_fd);
+		return rc;
+	}
+
+	/* enable pull-up on GPIO7 */
+	sx150x_gpio_pull_up_set(g_i2c_fd, 7, 1);
+
+	if (sx150x_gpio_get(g_i2c_fd, 7) == 0) {
+		/* daughter board installed: PAs connected to IO2+3 */
+		g_pa_gpio_offset = 2;
+	} else {
+		/* PAs directly connected to 0+1 */
+		g_pa_gpio_offset = 0;
+	}
+
+	/* set both as output */
+	sx150x_gpio_direction_set(g_i2c_fd, g_pa_gpio_offset, SX150x_DIR_OUTPUT);
+	sx150x_gpio_direction_set(g_i2c_fd, g_pa_gpio_offset+1, SX150x_DIR_OUTPUT);
+
+	/* disable them as default */
+	sob_bts_pa_enable(0, 0);
+	sob_bts_pa_enable(1, 0);
+
+	return 0;
+}