Support for a dallas/maxim onewire sensor, enough of it to
fool linux's w1-gpio driver
Signed-off-by: Michel Pollet <buser...@gmail.com>
---
hw/misc/Makefile.objs | 2 +
hw/misc/w1-ds18s20.c | 332
++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 334 insertions(+)
create mode 100644 hw/misc/w1-ds18s20.c
diff --git a/hw/misc/Makefile.objs b/hw/misc/Makefile.objs
index f674365..b42c231 100644
--- a/hw/misc/Makefile.objs
+++ b/hw/misc/Makefile.objs
@@ -42,3 +42,5 @@ obj-$(CONFIG_SLAVIO) += slavio_misc.o
obj-$(CONFIG_ZYNQ) += zynq_slcr.o
obj-$(CONFIG_PVPANIC) += pvpanic.o
+
+obj-y += w1-ds18s20.o
diff --git a/hw/misc/w1-ds18s20.c b/hw/misc/w1-ds18s20.c
new file mode 100644
index 0000000..cea3d6e
--- /dev/null
+++ b/hw/misc/w1-ds18s20.c
@@ -0,0 +1,332 @@
+/*
+ * w1-ds18s20.c
+ *
+ * Copyright: Michel Pollet <buser...@gmail.com>
+ *
+ * QEMU Licence
+ */
+
+/*
+ * This device will behave like a DS18S20 onewire temperature sensor,
+ * Linux's w1-gpio driver will be fooled into talking to it.
+ *
+ * w1-gpio (and other onewire masters?) attempts to fudge the bit timing
+ * to try to adapt to 'bad' wires, most real hardware sensors must have a
+ * PLL of sort are seems to be able to adapt, this implementation doesn't
+ * and 'sometime' drops from the bus for a short time, in a way it's
+ * rather nice as it simulates a moderately bad wire.
+ *
+ * To instantiate this driver, you just need one IRQ in and out, there
+ * is a second input IRQ to set the temperature. A nice 'todo' would
+ * possibly to have a monitor command to do so.
+ *
+ * Another nice todo would possibly be to handle a proper qemu 'bus'
+ * and have a way to specify the hardware ID of the device.
+ *
+ * Example instantiation for this device:
+ {
+ DeviceState * dev = sysbus_create_simple("ds18s20", -1, 0);
+
+ qdev_connect_gpio_out(gpio, GPIO_W1, qdev_get_gpio_in(dev, 0));
+ qdev_connect_gpio_out(dev, 0, qdev_get_gpio_in(gpio, GPIO_W1));
+ }
+ * Test case (assuming your w1-gpio knows it's GPIO from a .dts):
+ / # modprobe w1-therm
+ / # modprobe w1-gpio
+ / # cat /sys/bus/w1/devices/28-deadbeeff00d/w1_slave
+ 50 05 8d e0 ff fd 03 40 14 : crc=cb NO
+ 00 00 00 00 00 00 00 00 00 t=85000
+ / # cat /sys/bus/w1/devices/28-deadbeeff00d/w1_slave
+ 50 05 0d f0 7f ff 00 10 45 : crc=45 YES
+ 50 05 0d f0 7f ff 00 10 45 t=85000
+ *
+ */
+#include "hw/sysbus.h"
+
+
+#define D(w)
+
+typedef struct OneWireDevice {
+ SysBusDevice busdev;
+ MemoryRegion dummy_iomem;
+
+ qemu_irq out;
+
+ int current_temp_mc; // in millicelcius
+ uint64_t w1_id; // full w1 ID, including CRC
+ uint64_t w1_id_received; // for comparisons
+ int muted; // set to 1 when 'offline' awaiting
start
+ int addr_bit; // current address bit sent/received
+
+ int64_t stamp; // timestamp of last low edge
+
+ uint8_t write_buffer; // incoming bits from master
+ int write_count;
+ uint64_t read_buffer; // outgoing bits to master
+ int read_count;
+ uint8_t read_crc; // CRC, for scratchpad
+ uint8_t command; // current command
+} OneWireDevice;
+
+enum {
+ W1_CMD_SEARCH_ROM = 0xf0,
+ W1_CMD_MATCH_ROM = 0x55,
+ W1_CMD_SKIP_ROM = 0xcc,
+ W1_CMD_READ_PSU = 0xb4,
+ W1_CMD_CONVERT_TEMP = 0x44,
+ W1_CMD_READ_SCRATCHPAD = 0xbe,
+ // MISSING "write scratchpad", unused in linux
+};
+
+/* CRC bits here were nicked from linux's */
+static uint8_t w1_crc8_table[] = {
+ 0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65,
+ 157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220,
+ 35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98,
+ 190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255,
+ 70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89,
7,
+ 219, 133, 103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196,
154,
+ 101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122,
36,
+ 248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231,
185,
+ 140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147,
205,
+ 17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14,
80,
+ 175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176,
238,
+ 50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45,
115,
+ 202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213,
139,
+ 87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72,
22,
+ 233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246,
168,
+ 116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107,
53
+};
+
+static uint8_t w1_calc_crc8(uint8_t * data, int len)
+{
+ uint8_t crc = 0;
+ while (len--)
+ crc = w1_crc8_table[crc ^ *data++];
+ return crc;
+}
+
+static uint8_t w1_calc_crc_le(uint64_t n, int len)
+{
+ int i;
+ uint8_t w1_id[8];
+ for (i = 0; i < len; i++) {
+ w1_id[i] = n >> (i * 8);
+ }
+ return w1_calc_crc8(w1_id, len);
+}
+
+static void w1_make_id(OneWireDevice * w, uint64 unique)
+{
+ uint8_t crc = w1_calc_crc_le(unique, 7);
+ w->w1_id = (unique & ~0xff00000000000000) | ((uint64_t)crc << 56);
+ D(printf("%s start id %016llx\n", __func__,
+ (long long int)w->w1_id);)
+}
+
+static void w1_receive(void *opaque, int irq, int level)
+{
+ OneWireDevice * w = (OneWireDevice *)opaque;
+ int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+ int64_t duration = (now - w->stamp) / SCALE_US;
+
+ /* the IRQ 0 is for signalling, the second IRQ is to allow external
+ * code to set the temperature the sensor will return */
+ if (irq == 1) {
+ w->current_temp_mc = level;
+ return;
+ }
+ if (level == 0) {
+ w->stamp = now;
+ qemu_irq_raise(w->out);
+ return;
+ }
+
+ /*
+ * First detect whether this is a reset, a read 0/1 or a write 0/1
+ * These timings are straight from the datasheet, however, the
+ * master driver has a tendency to vary the timings, presumably
+ * to allow bad wires and so on.
+ */
+ if (duration >= 480) { // init sequence
+ D(printf("%s init pulse %d us\n", __func__, (int)duration);)
+ w->command = 0;
+ qemu_irq_lower(w->out);
+ w->write_count = w->read_count = 0;
+ w->write_buffer = w->read_buffer = 0;
+ w->muted = 0;
+ } else if (!w->muted) {
+ if (duration > 40) { // write 0 slot
+ w->write_buffer >>= 1;
+ w->write_count++;
+ } else if (duration > 1) {
+ if (w->read_count) { // read bit slot
+ qemu_set_irq(w->out, w->read_buffer & 1);
+ w->read_buffer >>= 1;
+ w->read_count--;
+ } else { // write 1 slot
+ w->write_buffer = (w->write_buffer >> 1) | 0x80;
+ w->write_count++;
+ }
+ }
+ }
+
+ /*
+ * If we've received 8 bits, check to see if we're in command
+ * mode, and start that command processing.
+ */
+ if (w->write_count == 8) {
+ // printf("%s BYTE %02x\n", __func__, w->write_buffer);
+ w->command = w->write_buffer;
+ w->write_count = 0;
+ switch (w->command) {
+ case W1_CMD_SEARCH_ROM:
+ w->addr_bit = 0;
+ w->read_count = 0;
+ w->w1_id_received = 0;
+ // printf("%s SEARCH_ROM start id %016llx\n", __func__,
+ // (long long int)w->w1_id);
+ break;
+ case W1_CMD_MATCH_ROM:
+ w->addr_bit = 0;
+ w->read_count = 0;
+ w->w1_id_received = 0;
+ D(printf("%s MATCH_ROM start id %016llx\n", __func__,
+ (long long int)w->w1_id);)
+ break;
+ case W1_CMD_SKIP_ROM: // it's like we match. w00t
+ w->w1_id_received = w->w1_id;
+ w->muted = 0;
+ D(printf("%s SKIP_ROM\n", __func__);)
+ break;
+ case W1_CMD_READ_PSU:
+ w->read_count = 1;
+ w->read_buffer = 1; // 0: parasite power, 1: power pin
+ D(printf("%s READ_PSU\n", __func__);)
+ break;
+ case W1_CMD_CONVERT_TEMP:
+ w->read_count = 3;
+ w->read_buffer = 0x4; // send 2 busy and 1 'done' bit, for
a laugh
+ D(printf("%s CONVERT_TEMP\n", __func__);)
+ break;
+ case W1_CMD_READ_SCRATCHPAD:
+ w->read_count = 64;
+ w->read_buffer = 0x1000ff7ff00d0000 +
+ (((w->current_temp_mc * 0x7d0) / 125000) & 0xffff);
+ w->read_crc = w1_calc_crc_le(w->read_buffer, 8);
+ D(printf("%s READ_SCRATCHPAD %016llx crc %02x\n", __func__,
+ (long long int)w->read_buffer, w->read_crc);)
+ break;
+ default:
+ D(printf("%s unknown w1 command code %02x\n", __func__,
w->command);)
+ break;
+ }
+ w->write_buffer = 0;
+ }
+ /*
+ * Ongoing commands are processed here
+ */
+ switch (w->command) {
+ case W1_CMD_SEARCH_ROM:
+ // still transmitting an address bit
+ if (w->read_count > 0) {
+ break;
+ }
+ // if we have received the ack bit, OR it is the first bit,
+ // then try to send another one until we're done
+ if (w->write_count == 1 || w->addr_bit == 0) {
+ if (w->write_count) {
+ w->w1_id_received = (w->w1_id_received >> 1) |
+ (((uint64_t)w->write_buffer >> 7) << 63);
+ if ((w->write_buffer >> 7) !=
+ (int)((w->w1_id >> (w->addr_bit-1)) & 1)) {
+ // printf("%s NOT MATCHED bit %d muting\n",
__func__, w->addr_bit-1);
+ w->command = 0;
+ w->muted = 1;
+ break;
+ }
+ w->write_buffer = 0;
+ w->write_count = 0;
+ if (w->addr_bit == 64) {
+ D(printf("%s SEARCH_ROM done %016llx / %016llx\n",
__func__,
+ (long long int)w->w1_id_received,
+ (long long int)w->w1_id);)
+ w->command = 0;
+ break;
+ }
+ }
+ uint8_t bit = (w->w1_id >> w->addr_bit) & 1;
+ w->read_buffer = bit | (!bit << 1);
+ w->read_count = 2;
+ w->addr_bit++;
+ }
+ break;
+ case W1_CMD_MATCH_ROM:
+ if (w->write_count) {
+ w->w1_id_received = (w->w1_id_received >> 1) |
+ (((uint64_t)w->write_buffer >> 7) << 63);
+ w->write_buffer = 0;
+ w->write_count = 0;
+ if (w->addr_bit == 64) {
+ D(printf("%s W1_CMD_MATCH_ROM done %016llx /
%016llx\n", __func__,
+ (long long int)w->w1_id_received,
+ (long long int)w->w1_id);)
+ w->command = 0;
+ w->muted = w->w1_id_received != w->w1_id;
+ break;
+ }
+ }
+ break;
+ case W1_CMD_READ_SCRATCHPAD:
+ if (w->read_count != 0) {
+ break;
+ }
+ D(printf("%s READ_SCRATCHPAD send CRC\n", __func__);)
+ w->read_count = 8;
+ w->read_buffer = w->read_crc;
+ w->command = 0;
+ break;
+ }
+}
+
+static int
+w1_device_init(SysBusDevice *dev)
+{
+ OneWireDevice * w = OBJECT_CHECK(OneWireDevice, dev, "ds18s20");
+ DeviceState *qdev = DEVICE(dev);
+
+ memory_region_init(&w->dummy_iomem, OBJECT(w), "w1_device", 0);
+ sysbus_init_mmio(dev, &w->dummy_iomem);
+
+ qdev_init_gpio_in(qdev, w1_receive, 2);
+ qdev_init_gpio_out(qdev, &w->out, 1);
+
+ /* The 0x28 there is the important bit, it's for thermal sensor family
*/
+ w1_make_id(w, 0x00deadbeeff00d28);
+ w->current_temp_mc = 85000; // reset value
+ return 0;
+}
+
+
+static void w1_device_class_init(ObjectClass *klass, void *data)
+{
+ DeviceClass *dc = DEVICE_CLASS(klass);
+ SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
+
+ k->init = w1_device_init;
+ dc->desc = "Virtual 1-Wire DS18S20 Thermal Sensor";
+}
+
+static TypeInfo w1_device_info = {
+ .name = "ds18s20",
+ .parent = TYPE_SYS_BUS_DEVICE,
+ .instance_size = sizeof(OneWireDevice),
+ .class_init = w1_device_class_init,
+};
+
+static void w1_device_register_type(void)
+{
+ type_register_static(&w1_device_info);
+}
+
+type_init(w1_device_register_type)
--
1.8.4.3
