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.

7 files changed, 621 insertions, 2 deletions

diff --git a/src/osmo-bts-sysmo/Makefile.am b/src/osmo-bts-sysmo/Makefile.am
index 68e3ce64..83c557fd 100644
--- a/src/osmo-bts-sysmo/Makefile.am
+++ b/src/osmo-bts-sysmo/Makefile.am
@@ -4,9 +4,10 @@ COMMON_LDADD = $(LIBOSMOCORE_LIBS) $(LIBOSMOGSM_LIBS) $(LIBOSMOVTY_LIBS) $(LIBOS
 
 EXTRA_DIST = misc/sysmobts_mgr.h misc/sysmobts_misc.h misc/sysmobts_par.h \
 	misc/sysmobts_eeprom.h misc/sysmobts_nl.h femtobts.h hw_misc.h \
-	l1_fwd.h l1_if.h l1_transp.h eeprom.h utils.h oml_router.h
+	l1_fwd.h l1_if.h l1_transp.h eeprom.h utils.h oml_router.h \
+	misc/sx150x.h misc/sob_bts_pa.h misc/i2c-dev.h
 
-bin_PROGRAMS = sysmobts sysmobts-remote l1fwd-proxy sysmobts-mgr sysmobts-util
+bin_PROGRAMS = sysmobts sysmobts-remote l1fwd-proxy sysmobts-mgr sysmobts-util sob-bts-pa-ctrl
 
 COMMON_SOURCES = main.c femtobts.c l1_if.c oml.c sysmobts_vty.c tch.c hw_misc.c calib_file.c \
 		 eeprom.c calib_fixup.c utils.c misc/sysmobts_par.c oml_router.c sysmobts_ctrl.c
@@ -33,3 +34,5 @@ sysmobts_mgr_LDADD = $(LIBGPS_LIBS) $(LIBOSMOCORE_LIBS) $(LIBOSMOVTY_LIBS) $(LIB
 
 sysmobts_util_SOURCES = misc/sysmobts_util.c misc/sysmobts_par.c eeprom.c
 sysmobts_util_LDADD = $(LIBOSMOCORE_LIBS)
+
+sob_bts_pa_ctrl_SOURCES = misc/sx150x.c misc/sob_bts_pa.c misc/sob_bts_pa_ctrl.c
diff --git a/src/osmo-bts-sysmo/misc/i2c-dev.h b/src/osmo-bts-sysmo/misc/i2c-dev.h
new file mode 100644
index 00000000..b9358174
--- /dev/null
+++ b/src/osmo-bts-sysmo/misc/i2c-dev.h
@@ -0,0 +1,335 @@
+/*
+    i2c-dev.h - i2c-bus driver, char device interface
+
+    Copyright (C) 1995-97 Simon G. Vogl
+    Copyright (C) 1998-99 Frodo Looijaard <frodol@dds.nl>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+    MA 02110-1301 USA.
+*/
+
+/* $Id: i2c-dev.h 5894 2010-12-12 13:22:29Z khali $ */
+
+#ifndef LIB_I2CDEV_H
+#define LIB_I2CDEV_H
+
+#include <linux/types.h>
+#include <sys/ioctl.h>
+
+
+/* -- i2c.h -- */
+
+
+/*
+ * I2C Message - used for pure i2c transaction, also from /dev interface
+ */
+struct i2c_msg {
+	__u16 addr;	/* slave address			*/
+	unsigned short flags;		
+#define I2C_M_TEN	0x10	/* we have a ten bit chip address	*/
+#define I2C_M_RD	0x01
+#define I2C_M_NOSTART	0x4000
+#define I2C_M_REV_DIR_ADDR	0x2000
+#define I2C_M_IGNORE_NAK	0x1000
+#define I2C_M_NO_RD_ACK		0x0800
+	short len;		/* msg length				*/
+	char *buf;		/* pointer to msg data			*/
+};
+
+/* To determine what functionality is present */
+
+#define I2C_FUNC_I2C			0x00000001
+#define I2C_FUNC_10BIT_ADDR		0x00000002
+#define I2C_FUNC_PROTOCOL_MANGLING	0x00000004 /* I2C_M_{REV_DIR_ADDR,NOSTART,..} */
+#define I2C_FUNC_SMBUS_PEC		0x00000008
+#define I2C_FUNC_SMBUS_BLOCK_PROC_CALL	0x00008000 /* SMBus 2.0 */
+#define I2C_FUNC_SMBUS_QUICK		0x00010000 
+#define I2C_FUNC_SMBUS_READ_BYTE	0x00020000 
+#define I2C_FUNC_SMBUS_WRITE_BYTE	0x00040000 
+#define I2C_FUNC_SMBUS_READ_BYTE_DATA	0x00080000 
+#define I2C_FUNC_SMBUS_WRITE_BYTE_DATA	0x00100000 
+#define I2C_FUNC_SMBUS_READ_WORD_DATA	0x00200000 
+#define I2C_FUNC_SMBUS_WRITE_WORD_DATA	0x00400000 
+#define I2C_FUNC_SMBUS_PROC_CALL	0x00800000 
+#define I2C_FUNC_SMBUS_READ_BLOCK_DATA	0x01000000 
+#define I2C_FUNC_SMBUS_WRITE_BLOCK_DATA 0x02000000 
+#define I2C_FUNC_SMBUS_READ_I2C_BLOCK	0x04000000 /* I2C-like block xfer  */
+#define I2C_FUNC_SMBUS_WRITE_I2C_BLOCK	0x08000000 /* w/ 1-byte reg. addr. */
+
+#define I2C_FUNC_SMBUS_BYTE (I2C_FUNC_SMBUS_READ_BYTE | \
+                             I2C_FUNC_SMBUS_WRITE_BYTE)
+#define I2C_FUNC_SMBUS_BYTE_DATA (I2C_FUNC_SMBUS_READ_BYTE_DATA | \
+                                  I2C_FUNC_SMBUS_WRITE_BYTE_DATA)
+#define I2C_FUNC_SMBUS_WORD_DATA (I2C_FUNC_SMBUS_READ_WORD_DATA | \
+                                  I2C_FUNC_SMBUS_WRITE_WORD_DATA)
+#define I2C_FUNC_SMBUS_BLOCK_DATA (I2C_FUNC_SMBUS_READ_BLOCK_DATA | \
+                                   I2C_FUNC_SMBUS_WRITE_BLOCK_DATA)
+#define I2C_FUNC_SMBUS_I2C_BLOCK (I2C_FUNC_SMBUS_READ_I2C_BLOCK | \
+                                  I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)
+
+/* Old name, for compatibility */
+#define I2C_FUNC_SMBUS_HWPEC_CALC	I2C_FUNC_SMBUS_PEC
+
+/* 
+ * Data for SMBus Messages 
+ */
+#define I2C_SMBUS_BLOCK_MAX	32	/* As specified in SMBus standard */	
+#define I2C_SMBUS_I2C_BLOCK_MAX	32	/* Not specified but we use same structure */
+union i2c_smbus_data {
+	__u8 byte;
+	__u16 word;
+	__u8 block[I2C_SMBUS_BLOCK_MAX + 2]; /* block[0] is used for length */
+	                                            /* and one more for PEC */
+};
+
+/* smbus_access read or write markers */
+#define I2C_SMBUS_READ	1
+#define I2C_SMBUS_WRITE	0
+
+/* SMBus transaction types (size parameter in the above functions) 
+   Note: these no longer correspond to the (arbitrary) PIIX4 internal codes! */
+#define I2C_SMBUS_QUICK		    0
+#define I2C_SMBUS_BYTE		    1
+#define I2C_SMBUS_BYTE_DATA	    2 
+#define I2C_SMBUS_WORD_DATA	    3
+#define I2C_SMBUS_PROC_CALL	    4
+#define I2C_SMBUS_BLOCK_DATA	    5
+#define I2C_SMBUS_I2C_BLOCK_BROKEN  6
+#define I2C_SMBUS_BLOCK_PROC_CALL   7		/* SMBus 2.0 */
+#define I2C_SMBUS_I2C_BLOCK_DATA    8
+
+
+/* ----- commands for the ioctl like i2c_command call:
+ * note that additional calls are defined in the algorithm and hw 
+ *	dependent layers - these can be listed here, or see the 
+ *	corresponding header files.
+ */
+				/* -> bit-adapter specific ioctls	*/
+#define I2C_RETRIES	0x0701	/* number of times a device address      */
+				/* should be polled when not            */
+                                /* acknowledging 			*/
+#define I2C_TIMEOUT	0x0702	/* set timeout - call with int 		*/
+
+
+/* this is for i2c-dev.c	*/
+#define I2C_SLAVE	0x0703	/* Change slave address			*/
+				/* Attn.: Slave address is 7 or 10 bits */
+#define I2C_SLAVE_FORCE	0x0706	/* Change slave address			*/
+				/* Attn.: Slave address is 7 or 10 bits */
+				/* This changes the address, even if it */
+				/* is already taken!			*/
+#define I2C_TENBIT	0x0704	/* 0 for 7 bit addrs, != 0 for 10 bit	*/
+
+#define I2C_FUNCS	0x0705	/* Get the adapter functionality */
+#define I2C_RDWR	0x0707	/* Combined R/W transfer (one stop only)*/
+#define I2C_PEC		0x0708	/* != 0 for SMBus PEC                   */
+
+#define I2C_SMBUS	0x0720	/* SMBus-level access */
+
+/* -- i2c.h -- */
+
+
+/* Note: 10-bit addresses are NOT supported! */
+
+/* This is the structure as used in the I2C_SMBUS ioctl call */
+struct i2c_smbus_ioctl_data {
+	char read_write;
+	__u8 command;
+	int size;
+	union i2c_smbus_data *data;
+};
+
+/* This is the structure as used in the I2C_RDWR ioctl call */
+struct i2c_rdwr_ioctl_data {
+	struct i2c_msg *msgs;	/* pointers to i2c_msgs */
+	int nmsgs;		/* number of i2c_msgs */
+};
+
+
+static inline __s32 i2c_smbus_access(int file, char read_write, __u8 command, 
+                                     int size, union i2c_smbus_data *data)
+{
+	struct i2c_smbus_ioctl_data args;
+
+	args.read_write = read_write;
+	args.command = command;
+	args.size = size;
+	args.data = data;
+	return ioctl(file,I2C_SMBUS,&args);
+}
+
+
+static inline __s32 i2c_smbus_write_quick(int file, __u8 value)
+{
+	return i2c_smbus_access(file,value,0,I2C_SMBUS_QUICK,NULL);
+}
+	
+static inline __s32 i2c_smbus_read_byte(int file)
+{
+	union i2c_smbus_data data;
+	if (i2c_smbus_access(file,I2C_SMBUS_READ,0,I2C_SMBUS_BYTE,&data))
+		return -1;
+	else
+		return 0x0FF & data.byte;
+}
+
+static inline __s32 i2c_smbus_write_byte(int file, __u8 value)
+{
+	return i2c_smbus_access(file,I2C_SMBUS_WRITE,value,
+	                        I2C_SMBUS_BYTE,NULL);
+}
+
+static inline __s32 i2c_smbus_read_byte_data(int file, __u8 command)
+{
+	union i2c_smbus_data data;
+	if (i2c_smbus_access(file,I2C_SMBUS_READ,command,
+	                     I2C_SMBUS_BYTE_DATA,&data))
+		return -1;
+	else
+		return 0x0FF & data.byte;
+}
+
+static inline __s32 i2c_smbus_write_byte_data(int file, __u8 command, 
+                                              __u8 value)
+{
+	union i2c_smbus_data data;
+	data.byte = value;
+	return i2c_smbus_access(file,I2C_SMBUS_WRITE,command,
+	                        I2C_SMBUS_BYTE_DATA, &data);
+}
+
+static inline __s32 i2c_smbus_read_word_data(int file, __u8 command)
+{
+	union i2c_smbus_data data;
+	if (i2c_smbus_access(file,I2C_SMBUS_READ,command,
+	                     I2C_SMBUS_WORD_DATA,&data))
+		return -1;
+	else
+		return 0x0FFFF & data.word;
+}
+
+static inline __s32 i2c_smbus_write_word_data(int file, __u8 command, 
+                                              __u16 value)
+{
+	union i2c_smbus_data data;
+	data.word = value;
+	return i2c_smbus_access(file,I2C_SMBUS_WRITE,command,
+	                        I2C_SMBUS_WORD_DATA, &data);
+}
+
+static inline __s32 i2c_smbus_process_call(int file, __u8 command, __u16 value)
+{
+	union i2c_smbus_data data;
+	data.word = value;
+	if (i2c_smbus_access(file,I2C_SMBUS_WRITE,command,
+	                     I2C_SMBUS_PROC_CALL,&data))
+		return -1;
+	else
+		return 0x0FFFF & data.word;
+}
+
+
+/* Returns the number of read bytes */
+static inline __s32 i2c_smbus_read_block_data(int file, __u8 command, 
+                                              __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i;
+	if (i2c_smbus_access(file,I2C_SMBUS_READ,command,
+	                     I2C_SMBUS_BLOCK_DATA,&data))
+		return -1;
+	else {
+		for (i = 1; i <= data.block[0]; i++)
+			values[i-1] = data.block[i];
+		return data.block[0];
+	}
+}
+
+static inline __s32 i2c_smbus_write_block_data(int file, __u8 command, 
+                                               __u8 length, const __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i;
+	if (length > 32)
+		length = 32;
+	for (i = 1; i <= length; i++)
+		data.block[i] = values[i-1];
+	data.block[0] = length;
+	return i2c_smbus_access(file,I2C_SMBUS_WRITE,command,
+	                        I2C_SMBUS_BLOCK_DATA, &data);
+}
+
+/* Returns the number of read bytes */
+/* Until kernel 2.6.22, the length is hardcoded to 32 bytes. If you
+   ask for less than 32 bytes, your code will only work with kernels
+   2.6.23 and later. */
+static inline __s32 i2c_smbus_read_i2c_block_data(int file, __u8 command,
+                                                  __u8 length, __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i;
+
+	if (length > 32)
+		length = 32;
+	data.block[0] = length;
+	if (i2c_smbus_access(file,I2C_SMBUS_READ,command,
+	                     length == 32 ? I2C_SMBUS_I2C_BLOCK_BROKEN :
+	                      I2C_SMBUS_I2C_BLOCK_DATA,&data))
+		return -1;
+	else {
+		for (i = 1; i <= data.block[0]; i++)
+			values[i-1] = data.block[i];
+		return data.block[0];
+	}
+}
+
+static inline __s32 i2c_smbus_write_i2c_block_data(int file, __u8 command,
+                                                   __u8 length,
+                                                   const __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i;
+	if (length > 32)
+		length = 32;
+	for (i = 1; i <= length; i++)
+		data.block[i] = values[i-1];
+	data.block[0] = length;
+	return i2c_smbus_access(file,I2C_SMBUS_WRITE,command,
+	                        I2C_SMBUS_I2C_BLOCK_BROKEN, &data);
+}
+
+/* Returns the number of read bytes */
+static inline __s32 i2c_smbus_block_process_call(int file, __u8 command,
+                                                 __u8 length, __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i;
+	if (length > 32)
+		length = 32;
+	for (i = 1; i <= length; i++)
+		data.block[i] = values[i-1];
+	data.block[0] = length;
+	if (i2c_smbus_access(file,I2C_SMBUS_WRITE,command,
+	                     I2C_SMBUS_BLOCK_PROC_CALL,&data))
+		return -1;
+	else {
+		for (i = 1; i <= data.block[0]; i++)
+			values[i-1] = data.block[i];
+		return data.block[0];
+	}
+}
+
+
+#endif /* LIB_I2CDEV_H */
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;
+}
diff --git a/src/osmo-bts-sysmo/misc/sob_bts_pa.h b/src/osmo-bts-sysmo/misc/sob_bts_pa.h
new file mode 100644
index 00000000..3f918dc8
--- /dev/null
+++ b/src/osmo-bts-sysmo/misc/sob_bts_pa.h
@@ -0,0 +1,4 @@
+#pragma once
+
+int sob_bts_pa_init(int adapter_nr);
+int sob_bts_pa_enable(int pa_num, int enable);
diff --git a/src/osmo-bts-sysmo/misc/sob_bts_pa_ctrl.c b/src/osmo-bts-sysmo/misc/sob_bts_pa_ctrl.c
new file mode 100644
index 00000000..316ba264
--- /dev/null
+++ b/src/osmo-bts-sysmo/misc/sob_bts_pa_ctrl.c
@@ -0,0 +1,48 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+#include "sob_bts_pa.h"
+
+static void print_help(const char *cmdname)
+{
+	printf("%s <0-1> <on|off>\n", cmdname);
+}
+
+int main(int argc, char **argv)
+{
+	int rc;
+	int pa_nr, on;
+
+	if (argc < 3)
+		goto err_param;
+
+	pa_nr = atoi(argv[1]);
+	if (pa_nr < 0 || pa_nr > 1)
+		goto err_param;
+
+	if (!strcmp(argv[2], "on"))
+		on = 1;
+	else if (!strcmp(argv[2], "off"))
+		on = 0;
+	else
+		goto err_param;
+
+	rc = sob_bts_pa_init(1);
+	if (rc < 0)
+		exit(1);
+
+	printf("%sabling SOB-BTS PA #%u\n", on? "en" : "dis", pa_nr);
+	rc = sob_bts_pa_enable(pa_nr, on);
+	if (rc < 0) {
+		fprintf(stderr, "Error during PA operation\n");
+		exit(1);
+	}
+
+	exit(0);
+
+err_param:
+	print_help(argv[0]);
+	exit(2);
+}
diff --git a/src/osmo-bts-sysmo/misc/sx150x.c b/src/osmo-bts-sysmo/misc/sx150x.c
new file mode 100644
index 00000000..be26d28b
--- /dev/null
+++ b/src/osmo-bts-sysmo/misc/sx150x.c
@@ -0,0 +1,137 @@
+/* sx150x - minimal SX150x I2C GPIO expander driver
+ * (C) 2015 by sysmocom - s.f.m.c. GmbH, Author: Harald Welte
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <limits.h>
+#include <fcntl.h>
+#include <getopt.h>
+
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+
+/* #include <linux/i2c-dev.h> */
+#include "i2c-dev.h"
+
+#include "sx150x.h"
+
+enum sx150x_reg {
+	SX150x_REG_DATA		= 0x00,
+	SX150x_REG_DIRECTION	= 0x01,
+	SX150x_REG_PULL_UP	= 0x02,
+	SX150x_REG_PULL_DOWN	= 0x03,
+	/* resered */
+	SX150x_REG_IRQ_MASK	= 0x05,
+	SX150x_REG_SENSE_HIGH	= 0x06,
+	SX150x_REG_SENSE_LOW	= 0x07,
+	SX150x_REG_IRQ_SOURCE	= 0x08,
+	SX150x_REG_EVENT_STATUS	= 0x09,
+	/* what about 0x0a - 0x0f? */
+	SX150x_REG_PLD_MODE	= 0x10,
+	SX150x_REG_PLD_TABLE0	= 0x11,
+	SX150x_REG_PLD_TABLE1	= 0x12,
+	SX150x_REG_PLD_TABLE2	= 0x13,
+	SX150x_REG_PLD_TABLE3	= 0x13,
+	SX150x_REG_PLD_TABLE4	= 0x13,
+	SX150x_REG_ADVANCED	= 0xAB,
+};
+
+int sx150x_gpio_direction_set(int fd, int gpio, enum sx150x_direction dir)
+{
+	int rc;
+
+	rc = i2c_smbus_read_byte_data(fd, SX150x_REG_DIRECTION);
+	if (rc < 0)
+		return rc;
+
+	rc &= ~(1 << gpio);
+	rc |= (dir << gpio);
+
+	return i2c_smbus_write_byte_data(fd, SX150x_REG_DIRECTION, rc);
+}
+
+int sx150x_gpio_direction_get(int fd, int gpio)
+{
+	int rc;
+
+	rc = i2c_smbus_read_byte_data(fd, SX150x_REG_DIRECTION);
+	if (rc < 0)
+		return rc;
+	return (rc & (1 << gpio));
+}
+
+int sx150x_gpio_pull_up_set(int fd, int gpio, int on)
+{
+	int rc;
+
+	rc = i2c_smbus_read_byte_data(fd, SX150x_REG_PULL_UP);
+	if (rc < 0)
+		return rc;
+
+	if (on)
+		rc |= (1 << gpio);
+	else
+		rc &= ~(1 << gpio);
+
+	return i2c_smbus_write_byte_data(fd, SX150x_REG_PULL_UP, rc);
+}
+
+int sx150x_gpio_pull_down_set(int fd, int gpio, int on)
+{
+	int rc;
+
+	rc = i2c_smbus_read_byte_data(fd, SX150x_REG_PULL_DOWN);
+	if (rc < 0)
+		return rc;
+
+	if (on)
+		rc |= (1 << gpio);
+	else
+		rc &= ~(1 << gpio);
+
+	return i2c_smbus_write_byte_data(fd, SX150x_REG_PULL_DOWN, rc);
+}
+
+int sx150x_gpio_set(int fd, int gpio, int high)
+{
+	int rc;
+
+	rc = i2c_smbus_read_byte_data(fd, SX150x_REG_DATA);
+	if (rc < 0)
+		return rc;
+
+	if (high)
+		rc |= (1 << gpio);
+	else
+		rc &= ~(1 << gpio);
+
+	return i2c_smbus_write_byte_data(fd, SX150x_REG_DATA, rc);
+}
+
+int sx150x_gpio_get(int fd, int gpio)
+{
+	int rc;
+
+	rc = i2c_smbus_read_byte_data(fd, SX150x_REG_DATA);
+	if (rc < 0)
+		return rc;
+	return (rc & (1 << gpio));
+}
diff --git a/src/osmo-bts-sysmo/misc/sx150x.h b/src/osmo-bts-sysmo/misc/sx150x.h
new file mode 100644
index 00000000..a3f57774
--- /dev/null
+++ b/src/osmo-bts-sysmo/misc/sx150x.h
@@ -0,0 +1,19 @@
+#pragma once
+#include <stdint.h>
+
+#define SX150x_ADDR_ADDR0	0x20
+#define SX150x_ADDR_ADDR1	0x21
+
+enum sx150x_direction {
+	SX150x_DIR_OUTPUT	= 0,
+	SX150x_DIR_INPUT	= 1
+};
+
+int sx150x_gpio_pull_up_set(int fd, int gpio, int on);
+int sx150x_gpio_pull_down_set(int fd, int gpio, int on);
+
+int sx150x_gpio_direction_set(int fd, int gpio, enum sx150x_direction dir);
+int sx150x_gpio_direction_get(int fd, int gpio);
+
+int sx150x_gpio_set(int fd, int gpio, int high);
+int sx150x_gpio_get(int fd, int gpio);