thermocouple: Add initial support for common SPI temperature sensing chips

Signed-off-by: Petri Honkala <cruwaller@gmail.com>
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/Makefile

@@ -3,6 +3,6 @@
 src-y += sched.c command.c basecmd.c debugcmds.c
 src-$(CONFIG_HAVE_GPIO) += gpiocmds.c stepper.c endstop.c
 src-$(CONFIG_HAVE_GPIO_ADC) += adccmds.c
-src-$(CONFIG_HAVE_GPIO_SPI) += spicmds.c
+src-$(CONFIG_HAVE_GPIO_SPI) += spicmds.c thermocouple.c
 src-$(CONFIG_HAVE_GPIO_HARD_PWM) += pwmcmds.c
 src-$(CONFIG_HAVE_USER_INTERFACE) += lcd_st7920.c lcd_hd44780.c buttons.c

src/spicmds.c

@@ -9,6 +9,7 @@
 #include "basecmd.h" // oid_alloc
 #include "command.h" // DECL_COMMAND
 #include "sched.h" // DECL_SHUTDOWN
+#include "spicmds.h" // spidev_transfer
 
 struct spidev_s {
     struct spi_config spi_config;
@@ -53,7 +54,13 @@ DECL_COMMAND(command_config_spi_without_cs,
              "config_spi_without_cs oid=%c bus=%u mode=%u rate=%u"
              " shutdown_msg=%*s");
 
-static void
+struct spidev_s *
+spidev_oid_lookup(uint8_t oid)
+{
+    return oid_lookup(oid, command_config_spi);
+}
+
+void
 spidev_transfer(struct spidev_s *spi, uint8_t receive_data
                 , uint8_t data_len, uint8_t *data)
 {

src/spicmds.h

@@ -0,0 +1,10 @@
+#ifndef __SPICMDS_H
+#define __SPICMDS_H
+
+#include <stdint.h> // uint8_t
+
+struct spidev_s *spidev_oid_lookup(uint8_t oid);
+void spidev_transfer(struct spidev_s *spi, uint8_t receive_data
+                     , uint8_t data_len, uint8_t *data);
+
+#endif // stepper.h

src/thermocouple.c

@@ -0,0 +1,178 @@
+// Basic support for common SPI controlled thermocouple chips
+//
+// Copyright (C) 2018  Petri Honkala <cruwaller@gmail.com>
+// Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include <string.h> // memcpy
+#include "board/irq.h" // irq_disable
+#include "basecmd.h" // oid_alloc
+#include "byteorder.h" // be32_to_cpu
+#include "command.h" // DECL_COMMAND
+#include "sched.h" // DECL_TASK
+#include "spicmds.h" // spidev_transfer
+
+enum {
+    TS_CHIP_MAX31855 = 1 << 0,
+    TS_CHIP_MAX31856 = 1 << 1,
+    TS_CHIP_MAX31865 = 1 << 2
+};
+
+struct thermocouple_spi {
+    struct timer timer;
+    uint32_t rest_time;
+    uint32_t min_value;           // Min allowed ADC value
+    uint32_t max_value;           // Max allowed ADC value
+    struct spidev_s *spi;
+    uint8_t chip_type, flags;
+};
+
+enum {
+    TS_PENDING = 1,
+};
+
+static struct task_wake thermocouple_wake;
+
+static uint_fast8_t thermocouple_event(struct timer *timer) {
+    struct thermocouple_spi *spi = container_of(
+            timer, struct thermocouple_spi, timer);
+    // Trigger task to read and send results
+    sched_wake_task(&thermocouple_wake);
+    spi->flags |= TS_PENDING;
+    spi->timer.waketime += spi->rest_time;
+    return SF_RESCHEDULE;
+}
+
+void
+command_config_thermocouple(uint32_t *args)
+{
+    uint8_t chip_type = args[2];
+    if (chip_type > TS_CHIP_MAX31865 || !chip_type)
+        shutdown("Invalid thermocouple chip type");
+    struct thermocouple_spi *spi = oid_alloc(
+        args[0], command_config_thermocouple, sizeof(*spi));
+    spi->timer.func = thermocouple_event;
+    spi->spi = spidev_oid_lookup(args[1]);
+    spi->chip_type = chip_type;
+}
+DECL_COMMAND(command_config_thermocouple,
+             "config_thermocouple oid=%c spi_oid=%c chip_type=%c");
+
+void
+command_query_thermocouple(uint32_t *args)
+{
+    struct thermocouple_spi *spi = oid_lookup(
+        args[0], command_config_thermocouple);
+
+    sched_del_timer(&spi->timer);
+    spi->timer.waketime = args[1];
+    if (! spi->timer.waketime)
+        return;
+    spi->rest_time = args[2];
+    spi->min_value = args[3];
+    spi->max_value = args[4];
+    sched_add_timer(&spi->timer);
+}
+DECL_COMMAND(command_query_thermocouple,
+             "query_thermocouple oid=%c clock=%u rest_ticks=%u"
+             " min_value=%u max_value=%u");
+
+static void
+thermocouple_respond(struct thermocouple_spi *spi, uint32_t next_begin_time
+                     , uint32_t value, uint8_t fault, uint8_t oid)
+{
+    /* check the result and stop if below or above allowed range */
+    if (value < spi->min_value || value > spi->max_value) {
+        try_shutdown("Thermocouple ADC out of range");
+    }
+    sendf("thermocouple_result oid=%c next_clock=%u value=%u fault=%c",
+          oid, next_begin_time, value, fault);
+}
+
+/* Logic of thermocouple K readers MAX6675 and MAX31855 are same */
+static void
+thermocouple_handle_max31855(struct thermocouple_spi *spi
+                             , uint32_t next_begin_time, uint8_t oid)
+{
+    uint8_t msg[4] = { 0x00, 0x00, 0x00, 0x00 };
+    spidev_transfer(spi->spi, 1, sizeof(msg), msg);
+    uint32_t value;
+    memcpy(&value, msg, sizeof(value));
+    value = be32_to_cpu(value);
+    thermocouple_respond(spi, next_begin_time, value, 0, oid);
+    // Kill after data send, host decode an error
+    if (value & 0x04)
+        try_shutdown("Thermocouple reader fault");
+}
+
+#define MAX31856_LTCBH_REG 0x0C
+#define MAX31856_SR_REG 0x0F
+
+static void
+thermocouple_handle_max31856(struct thermocouple_spi *spi
+                             , uint32_t next_begin_time, uint8_t oid)
+{
+    uint8_t msg[4] = { MAX31856_LTCBH_REG, 0x00, 0x00, 0x00 };
+    spidev_transfer(spi->spi, 1, sizeof(msg), msg);
+    uint32_t value;
+    memcpy(&value, msg, sizeof(value));
+    value = be32_to_cpu(value) & 0x00ffffff;
+    // Read faults
+    msg[0] = MAX31856_SR_REG;
+    msg[1] = 0x00;
+    spidev_transfer(spi->spi, 1, 2, msg);
+    thermocouple_respond(spi, next_begin_time, value, msg[1], oid);
+}
+
+#define MAX31865_RTDMSB_REG 0x01
+#define MAX31865_FAULTSTAT_REG 0x07
+
+static void
+thermocouple_handle_max31865(struct thermocouple_spi *spi
+                             , uint32_t next_begin_time, uint8_t oid)
+{
+    uint8_t msg[4] = { MAX31865_RTDMSB_REG, 0x00, 0x00, 0x00 };
+    spidev_transfer(spi->spi, 1, 3, msg);
+    uint32_t value;
+    memcpy(&value, msg, sizeof(value));
+    value = (be32_to_cpu(value) >> 8) & 0xffff;
+    // Read faults
+    msg[0] = MAX31865_FAULTSTAT_REG;
+    msg[1] = 0x00;
+    spidev_transfer(spi->spi, 1, 2, msg);
+    thermocouple_respond(spi, next_begin_time, value, msg[1], oid);
+    // Kill after data send, host decode an error
+    if (value & 0x0001)
+        try_shutdown("Thermocouple reader fault");
+}
+
+// task to read thermocouple and send response
+void
+thermocouple_task(void)
+{
+    if (!sched_check_wake(&thermocouple_wake))
+        return;
+    uint8_t oid;
+    struct thermocouple_spi *spi;
+    foreach_oid(oid, spi, command_config_thermocouple) {
+        if (!(spi->flags & TS_PENDING))
+            continue;
+        irq_disable();
+        uint32_t next_begin_time = spi->timer.waketime;
+        spi->flags &= ~TS_PENDING;
+        irq_enable();
+        switch (spi->chip_type) {
+        case TS_CHIP_MAX31855:
+            thermocouple_handle_max31855(spi, next_begin_time, oid);
+            break;
+        case TS_CHIP_MAX31856:
+            thermocouple_handle_max31856(spi, next_begin_time, oid);
+            break;
+        case TS_CHIP_MAX31865:
+            thermocouple_handle_max31865(spi, next_begin_time, oid);
+            break;
+        }
+    }
+}
+DECL_TASK(thermocouple_task);