[Qemu-devel] [PATCH v2] ipmi: add SET_SENSOR_READING command

[Cédric Le Goater]

SET_SENSOR_READING is a complex IPMI command (see IPMI spec 35.17)
which enables the host software to set the reading value and the event
status of sensors supporting it.

Below is a proposal for all the operations (reading, assert, deassert,
event data) with the following limitations :

 - No event are generated for threshold-based sensors. 
 - The case in which the BMC needs to generate its own events is not
   supported.
   
Signed-off-by: Cédric Le Goater <address@hidden>
---

 Corey,

 There is some progress but I didn't add a check on the value before
 generating events because we would not generate an event when only
 the event bytes change. 

 Changes since v1:
 
 - created copies of the reading and the assertion bits before
   committing the values
 - added some TODOs
 - handled inconsistent Event Data Bytes operation
 
 hw/ipmi/ipmi_bmc_sim.c |  213 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 213 insertions(+)

Index: qemu-powernv-2.9.git/hw/ipmi/ipmi_bmc_sim.c
===================================================================
--- qemu-powernv-2.9.git.orig/hw/ipmi/ipmi_bmc_sim.c
+++ qemu-powernv-2.9.git/hw/ipmi/ipmi_bmc_sim.c
@@ -45,6 +45,7 @@
 #define IPMI_CMD_GET_SENSOR_READING       0x2d
 #define IPMI_CMD_SET_SENSOR_TYPE          0x2e
 #define IPMI_CMD_GET_SENSOR_TYPE          0x2f
+#define IPMI_CMD_SET_SENSOR_READING       0x30
 
 /* #define IPMI_NETFN_APP             0x06 In ipmi.h */
 
@@ -1739,6 +1740,217 @@ static void get_sensor_type(IPMIBmcSim *
     rsp_buffer_push(rsp, sens->evt_reading_type_code);
 }
 
+/*
+ * bytes   parameter
+ *    1    sensor number
+ *    2    operation (see below for bits meaning)
+ *    3    sensor reading
+ *  4:5    assertion states (optional)
+ *  6:7    deassertion states (optional)
+ *  8:10   event data 1,2,3 (optional)
+ */
+static void set_sensor_reading(IPMIBmcSim *ibs,
+                               uint8_t *cmd, unsigned int cmd_len,
+                               RspBuffer *rsp)
+{
+    IPMISensor *sens;
+    uint8_t evd1 = 0;
+    uint8_t evd2 = 0;
+    uint8_t evd3 = 0;
+    uint8_t new_reading = 0;
+    uint16_t new_assert_states = 0;
+    uint16_t new_deassert_states = 0;
+    bool change_reading = false;
+    bool change_assert = false;
+    bool change_deassert = false;
+    enum {
+        SENSOR_GEN_EVENT_NONE,
+        SENSOR_GEN_EVENT_DATA,
+        SENSOR_GEN_EVENT_BMC,
+    } do_gen_event = SENSOR_GEN_EVENT_NONE;
+
+    if ((cmd[2] >= MAX_SENSORS) ||
+            !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
+        rsp_buffer_set_error(rsp, IPMI_CC_REQ_ENTRY_NOT_PRESENT);
+        return;
+    }
+
+    sens = ibs->sensors + cmd[2];
+
+    /* [1:0] Sensor Reading operation */
+    switch ((cmd[3]) & 0x3) {
+    case 0: /* Do not change */
+        break;
+    case 1: /* write given value to sensor reading byte */
+        new_reading = cmd[4];
+        if (sens->reading != new_reading) {
+            change_reading = true;
+        }
+        break;
+    case 2:
+    case 3:
+        rsp_buffer_set_error(rsp, IPMI_CC_INVALID_DATA_FIELD);
+        return;
+    }
+
+    /* [3:2] Deassertion bits operation */
+    switch ((cmd[3] >> 2) & 0x3) {
+    case 0: /* Do not change */
+        break;
+    case 1: /* write given value */
+        if (cmd_len > 7) {
+            new_deassert_states = cmd[7];
+            change_deassert = true;
+        }
+        if (cmd_len > 8) {
+            new_deassert_states |= (cmd[8] << 8);
+        }
+        break;
+
+    case 2: /* mask on */
+        if (cmd_len > 7) {
+            new_deassert_states = (sens->deassert_states | cmd[7]);
+            change_deassert = true;
+        }
+        if (cmd_len > 8) {
+            new_deassert_states |= (sens->deassert_states | (cmd[8] << 8));
+        }
+        break;
+
+    case 3: /* mask off */
+        if (cmd_len > 7) {
+            new_deassert_states = (sens->deassert_states & cmd[7]);
+            change_deassert = true;
+        }
+        if (cmd_len > 8) {
+            new_deassert_states |= (sens->deassert_states & (cmd[8] << 8));
+        }
+        break;
+    }
+
+    if (change_deassert && (new_deassert_states == sens->deassert_states)) {
+        change_deassert = false;
+    }
+
+    /* [5:4] Assertion bits operation */
+    switch ((cmd[3] >> 4) & 0x3) {
+    case 0: /* Do not change */
+        break;
+    case 1: /* write given value */
+        if (cmd_len > 5) {
+            new_assert_states = cmd[5];
+            change_assert = true;
+        }
+        if (cmd_len > 6) {
+            new_assert_states |= (cmd[6] << 8);
+        }
+        break;
+
+    case 2: /* mask on */
+        if (cmd_len > 5) {
+            new_assert_states = (sens->assert_states | cmd[5]);
+            change_assert = true;
+        }
+        if (cmd_len > 6) {
+            new_assert_states |= (sens->assert_states | (cmd[6] << 8));
+        }
+        break;
+
+    case 3: /* mask off */
+        if (cmd_len > 5) {
+            new_assert_states = (sens->assert_states & cmd[5]);
+            change_assert = true;
+        }
+        if (cmd_len > 6) {
+            new_assert_states |= (sens->assert_states & (cmd[6] << 8));
+        }
+        break;
+    }
+
+    if (change_assert && (new_assert_states == sens->assert_states)) {
+        change_assert = false;
+    }
+
+    if (cmd_len > 9) {
+        evd1 = cmd[9];
+    }
+    if (cmd_len > 10) {
+        evd2 = cmd[10];
+    }
+    if (cmd_len > 11) {
+        evd3 = cmd[11];
+    }
+
+    /* [7:6] Event Data Bytes operation */
+    switch ((cmd[3] >> 6) & 0x3) {
+    case 0: /* Don’t use Event Data bytes from this command. BMC will
+             * generate it's own Event Data bytes based on its sensor
+             * implementation.  */
+        evd1 = evd2 = evd3 = 0x0;
+        do_gen_event = SENSOR_GEN_EVENT_BMC;
+        break;
+    case 1: /* Write given values to event data bytes including bits
+             * [3:0] Event Data 1. */
+        do_gen_event = SENSOR_GEN_EVENT_DATA;
+        break;
+    case 2: /* Write given values to event data bytes excluding bits
+             * [3:0] Event Data 1. */
+        evd1 &= 0xf0;
+        do_gen_event = SENSOR_GEN_EVENT_DATA;
+        break;
+    case 3:
+        rsp_buffer_set_error(rsp, IPMI_CC_INVALID_DATA_FIELD);
+        return;
+    }
+
+    /* Event Data Bytes operation and parameter are inconsistent. The
+     * Specs are not clear on that topic but generating an error seems
+     * correct. */
+    if (do_gen_event == SENSOR_GEN_EVENT_DATA && cmd_len < 10) {
+        rsp_buffer_set_error(rsp, IPMI_CC_INVALID_DATA_FIELD);
+        return;
+    }
+
+    /* commit values */
+    if (change_reading) {
+        sens->reading = new_reading;
+    }
+
+    if (change_assert) {
+        sens->assert_states = new_assert_states;
+    }
+
+    if (change_deassert) {
+        sens->deassert_states = new_deassert_states;
+    }
+
+    /* TODO: handle threshold sensor */
+    if (!IPMI_SENSOR_IS_DISCRETE(sens)) {
+        return;
+    }
+
+    switch (do_gen_event) {
+    case SENSOR_GEN_EVENT_DATA: {
+        unsigned int bit = evd1 & 0xf;
+        uint16_t mask = (1 << bit);
+
+        if (sens->assert_states & mask & sens->assert_enable) {
+            gen_event(ibs, cmd[2], 0, evd1, evd2, evd3);
+        }
+
+        if (sens->deassert_states & mask & sens->deassert_enable) {
+            gen_event(ibs, cmd[2], 1, evd1, evd2, evd3);
+        }
+    }
+        break;
+    case SENSOR_GEN_EVENT_BMC:
+        /* TODO: generate event and event data bytes depending on the
+         * sensor */
+        break;
+    case SENSOR_GEN_EVENT_NONE:
+        break;
+    }
+}
 
 static const IPMICmdHandler chassis_cmds[] = {
     [IPMI_CMD_GET_CHASSIS_CAPABILITIES] = { chassis_capabilities },
@@ -1759,6 +1971,7 @@ static const IPMICmdHandler sensor_event
     [IPMI_CMD_GET_SENSOR_READING] = { get_sensor_reading, 3 },
     [IPMI_CMD_SET_SENSOR_TYPE] = { set_sensor_type, 5 },
     [IPMI_CMD_GET_SENSOR_TYPE] = { get_sensor_type, 3 },
+    [IPMI_CMD_SET_SENSOR_READING] = { set_sensor_reading, 5 },
 };
 static const IPMINetfn sensor_event_netfn = {
     .cmd_nums = ARRAY_SIZE(sensor_event_cmds),