baylibre-acme: Add support for probe factor setting.

[libsigrok.git] / src / hardware / baylibre-acme / protocol.c

diff --git a/src/hardware/baylibre-acme/protocol.c b/src/hardware/baylibre-acme/protocol.c
index 272a4ff655e10c48add576acd0916754d1850d4c..22af9f97f4ac708ef0d1e48e2555a02dc8f1464a 100644 (file)
--- a/src/hardware/baylibre-acme/protocol.c
+++ b/src/hardware/baylibre-acme/protocol.c
@@ -21,10 +21,12 @@
 #include <stdlib.h> /* strtol() */
 #include <errno.h>
 #include <fcntl.h> /* open(), etc... */
+#include <glib/gstdio.h>
 #include "protocol.h"
 
 struct channel_group_priv {
        int hwmon_num;
+       int probe_type;
 };
 
 struct channel_priv {
@@ -40,6 +42,9 @@ static const uint8_t temp_i2c_addrs[] = {
        0x0, 0x0, 0x0, 0x0, 0x4c, 0x49, 0x4f, 0x4b,
 };
 
+#define MOHM_TO_UOHM(x) ((x) * 1000)
+#define UOHM_TO_MOHM(x) ((x) / 1000)
+
 SR_PRIV uint8_t bl_acme_get_enrg_addr(int index)
 {
        return enrg_i2c_addrs[index];
@@ -212,6 +217,7 @@ SR_PRIV gboolean bl_acme_register_probe(struct sr_dev_inst *sdi, int type,
        cg = g_malloc0(sizeof(struct sr_channel_group));
        cgp = g_malloc0(sizeof(struct channel_group_priv));
        cgp->hwmon_num = hwmon;
+       cgp->probe_type = type;
        cg->name = g_strdup_printf("Probe_%d", prb_num);
        cg->priv = cgp;
 
@@ -231,6 +237,108 @@ SR_PRIV gboolean bl_acme_register_probe(struct sr_dev_inst *sdi, int type,
        return TRUE;
 }
 
+/*
+ * Sets path to the hwmon attribute if this channel group
+ * supports shunt resistance setting. The caller has to supply
+ * a valid GString.
+ */
+static int get_shunt_path(const struct sr_channel_group *cg, GString *path)
+{
+       struct channel_group_priv *cgp;
+       int ret = SR_OK, status;
+
+       cgp = cg->priv;
+
+       if (cgp->probe_type != PROBE_ENRG) {
+               sr_err("Probe doesn't support shunt resistance setting");
+               return SR_ERR_ARG;
+       }
+
+       g_string_append_printf(path,
+                              "/sys/class/hwmon/hwmon%d/shunt_resistor",
+                              cgp->hwmon_num);
+
+       /*
+        * The shunt_resistor sysfs attribute is available
+        * in the Linux kernel since version 3.20. We have
+        * to notify the user if this attribute is not
+        * present.
+        */
+       status = g_file_test(path->str, G_FILE_TEST_EXISTS);
+       if (!status) {
+               sr_err("shunt_resistance attribute not present please update "
+                      "your kernel to version >=3.20");
+               return SR_ERR_NA;
+       }
+
+       return ret;
+}
+
+SR_PRIV int bl_acme_get_shunt(const struct sr_channel_group *cg,
+                             uint64_t *shunt)
+{
+       GString *path = g_string_sized_new(64);
+       gchar *contents;
+       int status, ret = SR_OK;
+       GError *err = NULL;
+
+       status = get_shunt_path(cg, path);
+       if (status != SR_OK) {
+               ret = status;
+               goto out;
+       }
+
+       status = g_file_get_contents(path->str, &contents, NULL, &err);
+       if (!status) {
+               sr_err("Error reading shunt resistance: %s", err->message);
+               ret = SR_ERR_IO;
+               goto out;
+       }
+
+       *shunt = UOHM_TO_MOHM(strtol(contents, NULL, 10));
+
+out:
+       g_string_free(path, TRUE);
+       return ret;
+}
+
+SR_PRIV int bl_acme_set_shunt(const struct sr_channel_group *cg,
+                             uint64_t shunt)
+{
+       GString *path = g_string_sized_new(64);;
+       int status, ret = SR_OK;
+       FILE *fd;
+
+       status = get_shunt_path(cg, path);
+       if (status != SR_OK) {
+               ret = status;
+               goto out;
+       }
+
+       /*
+        * Can't use g_file_set_contents() here, as it calls open() with
+        * O_EXEC flag in a sysfs directory thus failing with EACCES.
+        */
+       fd = g_fopen(path->str, "w");
+       if (!fd) {
+               sr_err("Error opening %s: %s", path->str, strerror(errno));
+               g_string_free(path, TRUE);
+               return SR_ERR_IO;
+       }
+
+       g_string_free(path, TRUE);
+       g_fprintf(fd, "%llu\n", MOHM_TO_UOHM(shunt));
+       /*
+        * XXX There's no g_fclose() in GLib. This seems to work,
+        * but is it safe?
+        */
+       fclose(fd);
+
+out:
+       g_string_free(path, TRUE);
+       return ret;
+}
+
 static int channel_to_mq(struct sr_channel *ch)
 {
        struct channel_priv *chp;