Hi Kevin,
On 8/15/21 12:02 AM, Kevin Townsend wrote:
> This commit adds emulation of the magnetometer on the LSM303DLHC.
> It allows the magnetometer's X, Y and Z outputs to be set via the
> magn_x, magn_y and magn_z properties, as well as the 12-bit
> temperature output via the temperature property.
How do we use it?
> Signed-off-by: Kevin Townsend <kevin.towns...@linaro.org>
> ---
> hw/sensor/Kconfig | 4 +
> hw/sensor/lsm303dlhc_mag.c | 499 +++++++++++++++++++++++++++++++++++++
> hw/sensor/meson.build | 1 +
> 3 files changed, 504 insertions(+)
> create mode 100644 hw/sensor/lsm303dlhc_mag.c
>
> diff --git a/hw/sensor/Kconfig b/hw/sensor/Kconfig
> index a2b55a4fdb..f9d0177433 100644
> --- a/hw/sensor/Kconfig
> +++ b/hw/sensor/Kconfig
> @@ -17,3 +17,7 @@ config ADM1272
> config MAX34451
> bool
> depends on I2C
> +
> +config LSM303DLHC_MAG
> + bool
> + depends on I2C
> \ No newline at end of file
> diff --git a/hw/sensor/lsm303dlhc_mag.c b/hw/sensor/lsm303dlhc_mag.c
> new file mode 100644
> index 0000000000..20629b1c79
> --- /dev/null
> +++ b/hw/sensor/lsm303dlhc_mag.c
> @@ -0,0 +1,499 @@
> +/*
> + * LSM303DLHC I2C magnetometer.
> + *
> + * Copyright (C) 2021 Linaro Ltd.
> + * Written by Kevin Townsend <kevin.towns...@linaro.org>
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +/*
> + * The I2C address associated with this device is set on the command-line
> when
> + * initialising the machine, but the following address is standard: 0x1E.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "hw/i2c/i2c.h"
> +#include "migration/vmstate.h"
> +#include "qapi/error.h"
> +#include "qapi/visitor.h"
> +#include "qemu/module.h"
> +
> +/* #define DEBUG_LSM303DLHC_MAG */
> +
> +#ifdef DEBUG_LSM303DLHC_MAG
> +#define DPRINTK(FMT, ...) printf(TYPE_LSM303DLHC_MAG " : " FMT, ##
> __VA_ARGS__)
> +#else
> +#define DPRINTK(FMT, ...) do {} while (0)
Please don't use DPRINTK() but trace-events instead.
> +#endif
> +
> +/* Property Names */
> +#define LSM303DLHC_MSG_PROP_MAGX ("mag_x")
> +#define LSM303DLHC_MSG_PROP_MAGY ("mag_y")
> +#define LSM303DLHC_MSG_PROP_MAGZ ("mag_z")
> +#define LSM303DLHC_MSG_PROP_TEMP ("temperature")
> +
> +enum LSM303DLHC_Mag_Reg {
> + LSM303DLHC_MAG_REG_CRA = 0x00,
> + LSM303DLHC_MAG_REG_CRB = 0x01,
> + LSM303DLHC_MAG_REG_MR = 0x02,
> + LSM303DLHC_MAG_REG_OUT_X_H = 0x03,
> + LSM303DLHC_MAG_REG_OUT_X_L = 0x04,
> + LSM303DLHC_MAG_REG_OUT_Z_H = 0x05,
> + LSM303DLHC_MAG_REG_OUT_Z_L = 0x06,
> + LSM303DLHC_MAG_REG_OUT_Y_H = 0x07,
> + LSM303DLHC_MAG_REG_OUT_Y_L = 0x08,
> + LSM303DLHC_MAG_REG_SR = 0x09,
> + LSM303DLHC_MAG_REG_IRA = 0x0A,
> + LSM303DLHC_MAG_REG_IRB = 0x0B,
> + LSM303DLHC_MAG_REG_IRC = 0x0C,
> + LSM303DLHC_MAG_REG_TEMP_OUT_H = 0x31,
> + LSM303DLHC_MAG_REG_TEMP_OUT_L = 0x32
> +};
> +
> +typedef struct LSM303DLHC_Mag_State {
> + I2CSlave parent_obj;
> +
> + uint8_t cra;
> + uint8_t crb;
> + uint8_t mr;
> + int16_t x;
> + int16_t z;
> + int16_t y;
> + uint8_t sr;
> + uint8_t ira;
> + uint8_t irb;
> + uint8_t irc;
> + int16_t temperature;
What is the unit?
> + uint8_t len;
> + uint8_t buf[6];
> + uint8_t pointer;
> +} LSM303DLHC_Mag_State;
> +
> +/* 'TYPE_xxx' define is required by OBJECT_DECLARE_SIMPLE_TYPE. */
Hmm?
> +#define TYPE_LSM303DLHC_MAG "lsm303dlhc_mag"
> +OBJECT_DECLARE_SIMPLE_TYPE(LSM303DLHC_Mag_State, LSM303DLHC_MAG)
> +
> +/**
> + * @brief Get handler for the mag_* property. This will be called
> + * whenever the public 'mag_*' property is read, such as via
> + * qom-get in the QEMU monitor.
> + */
> +static void lsm303dlhc_mag_get_xyz(Object *obj, Visitor *v,
> + const char *name, void *opaque, Error **errp)
Invalid style alignment (multiple times in this patch).
> +{
> + LSM303DLHC_Mag_State *s = LSM303DLHC_MAG(obj);
> + int64_t value;
> +
> + if (strcmp(name, LSM303DLHC_MSG_PROP_MAGX) == 0) {
> + value = s->x;
> + } else if (strcmp(name, LSM303DLHC_MSG_PROP_MAGY) == 0) {
> + value = s->y;
> + } else if (strcmp(name, LSM303DLHC_MSG_PROP_MAGZ) == 0) {
> + value = s->z;
> + } else {
> + error_setg(errp, "unknown property: %s", name);
> + return;
> + }
> +
> + visit_type_int(v, name, &value, errp);
> +}
> +
> +/**
> + * @brief Set handler for the mag_* property. This will be called
> + * whenever the public 'mag_*' property is set, such as via
> + * qom-set in the QEMU monitor.
> + */
> +static void lsm303dlhc_mag_set_xyz(Object *obj, Visitor *v,
> + const char *name, void *opaque, Error **errp)
> +{
> + LSM303DLHC_Mag_State *s = LSM303DLHC_MAG(obj);
> + int64_t temp;
Instead of the confusing 'temp' name, why not name this variable
'pos', 'position' or generically 'value'?
> +
> + if (!visit_type_int(v, name, &temp, errp)) {
> + return;
> + }
> +
> + if (temp > 2047 || temp < -2048) {
> + error_setg(errp, "value %d lsb is out of range", temp);
> + return;
> + }
> +
> + if (strcmp(name, LSM303DLHC_MSG_PROP_MAGX) == 0) {
> + s->x = (int16_t)temp;
> + } else if (strcmp(name, LSM303DLHC_MSG_PROP_MAGY) == 0) {
> + s->y = (int16_t)temp;
> + } else if (strcmp(name, LSM303DLHC_MSG_PROP_MAGZ) == 0) {
> + s->z = (int16_t)temp;
> + } else {
> + error_setg(errp, "unknown property: %s", name);
> + return;
> + }
> +}
> +
> +/**
> + * @brief Get handler for the temperature property. This will be called
> + * whenever the public 'temperature' property is read, such as via
> + * qom-get in the QEMU monitor.
> + */
> +static void lsm303dlhc_mag_get_temperature(Object *obj, Visitor *v,
> + const char *name, void *opaque, Error **errp)
> +{
> + LSM303DLHC_Mag_State *s = LSM303DLHC_MAG(obj);
> + int64_t value;
> +
> + value = s->temperature;
> +
> + visit_type_int(v, name, &value, errp);
> +}
> +
> +/**
> + * @brief Set handler for the temperature property. This will be called
> + * whenever the public 'temperature' property is set, such as via
> + * qom-set in the QEMU monitor.
> + */
> +static void lsm303dlhc_mag_set_temperature(Object *obj, Visitor *v,
> + const char *name, void *opaque, Error **errp)
> +{
> + LSM303DLHC_Mag_State *s = LSM303DLHC_MAG(obj);
> + int64_t temp;
> +
> + if (!visit_type_int(v, name, &temp, errp)) {
> + return;
> + }
> +
> + if (temp > 2047 || temp < -2048) {
> + error_setg(errp, "value %d lsb is out of range (1 C = 8 lsb)", temp);
"1 C = 8 lsb" is irrelevant in the error message IMO.
> + return;
> + }
> +
> + s->temperature = (int16_t)temp;
> +}
> +
> +/**
> + * @brief Callback handler whenever a 'I2C_START_RECV' (read) event is
> received.
> + */
> +static void lsm303dlhc_mag_read(LSM303DLHC_Mag_State *s)
> +{
> + s->len = 0;
> +
> + /*
> + * The address pointer on the LSM303DLHC auto-increments whenever a byte
> + * is read, without the master device having to request the next address.
> + *
> + * The auto-increment process has the following logic:
> + *
> + * - if (s->pointer == 8) then s->pointer = 3
> + * - else: if (s->pointer >= 12) then s->pointer = 0
> + * - else: s->pointer += 1
> + *
> + * Reading an invalid address return 0.
> + *
> + * The auto-increment logic is only taken into account in this driver
> + * for the LSM303DLHC_MAG_REG_OUT_X_H and LSM303DLHC_MAG_REG_TEMP_OUT_H
> + * registers, which are the two common uses cases for it. Accessing
> either
> + * of these registers will also populate the rest of the related dataset.
> + */
> +
> + DPRINTK("Read: register = 0x%02x\n", s->pointer);
> +
> + switch (s->pointer) {
> + case LSM303DLHC_MAG_REG_CRA:
> + s->buf[s->len++] = s->cra;
> + break;
> + case LSM303DLHC_MAG_REG_CRB:
> + s->buf[s->len++] = s->crb;
> + break;
> + case LSM303DLHC_MAG_REG_MR:
> + s->buf[s->len++] = s->mr;
> + break;
> + case LSM303DLHC_MAG_REG_OUT_X_H:
> + s->buf[s->len++] = (uint8_t)(s->x >> 8);
> + s->buf[s->len++] = (uint8_t)(s->x);
Rather use the safer load/store API with explicit endianess:
stw_be_p(s->buf, s->x);
s->len += 2; // or sizeof(s->x)
> + s->buf[s->len++] = (uint8_t)(s->z >> 8);
> + s->buf[s->len++] = (uint8_t)(s->z);
> + s->buf[s->len++] = (uint8_t)(s->y >> 8);
> + s->buf[s->len++] = (uint8_t)(s->y);
> + break;
> + case LSM303DLHC_MAG_REG_OUT_X_L:
> + s->buf[s->len++] = (uint8_t)(s->x);
> + break;
> + case LSM303DLHC_MAG_REG_OUT_Z_H:
> + s->buf[s->len++] = (uint8_t)(s->z >> 8);
> + break;
> + case LSM303DLHC_MAG_REG_OUT_Z_L:
> + s->buf[s->len++] = (uint8_t)(s->z);
> + break;
> + case LSM303DLHC_MAG_REG_OUT_Y_H:
> + s->buf[s->len++] = (uint8_t)(s->y >> 8);
> + break;
> + case LSM303DLHC_MAG_REG_OUT_Y_L:
> + s->buf[s->len++] = (uint8_t)(s->y);
> + break;
> + case LSM303DLHC_MAG_REG_SR:
> + s->buf[s->len++] = s->sr;
> + break;
> + case LSM303DLHC_MAG_REG_IRA:
> + s->buf[s->len++] = s->ira;
> + break;
> + case LSM303DLHC_MAG_REG_IRB:
> + s->buf[s->len++] = s->irb;
> + break;
> + case LSM303DLHC_MAG_REG_IRC:
> + s->buf[s->len++] = s->irc;
> + break;
> + case LSM303DLHC_MAG_REG_TEMP_OUT_H:
> + if (s->cra & 0x80) {
What means this 0x80 magic value? Either use a definition
or document it with a comment.
> + s->buf[s->len++] = (uint8_t)(s->temperature >> 8);
> + s->buf[s->len++] = (uint8_t)(s->temperature & 0xf0);
> + } else {
> + s->buf[s->len++] = 0;
> + s->buf[s->len++] = 0;
> + }
> + break;
> + case LSM303DLHC_MAG_REG_TEMP_OUT_L:
> + if (s->cra & 0x80) {
> + s->buf[s->len++] = (uint8_t)(s->temperature & 0xf0);
> + } else {
> + s->buf[s->len++] = 0;
> + }
> + break;
> + default:
> + s->buf[s->len++] = 0;
> + break;
> + }
> +}
> +
> +/**
> + * @brief Callback handler when a device attempts to write to a register.
> + */
> +static void lsm303dlhc_mag_write(LSM303DLHC_Mag_State *s)
> +{
> + DPRINTK("Write: register = 0x%02x, value = 0x%02x\n",
> + s->pointer, s->buf[0]);
> +
> + switch (s->pointer) {
> + case LSM303DLHC_MAG_REG_CRA:
> + s->cra = s->buf[0];
> + break;
> + case LSM303DLHC_MAG_REG_CRB:
> + s->crb = s->buf[0];
> + break;
> + case LSM303DLHC_MAG_REG_MR:
> + s->mr = s->buf[0];
> + break;
> + case LSM303DLHC_MAG_REG_SR:
> + s->sr = s->buf[0];
> + break;
> + case LSM303DLHC_MAG_REG_IRA:
> + s->ira = s->buf[0];
> + break;
> + case LSM303DLHC_MAG_REG_IRB:
> + s->irb = s->buf[0];
> + break;
> + case LSM303DLHC_MAG_REG_IRC:
> + s->irc = s->buf[0];
> + break;
default:
qemu_log_mask(LOG_GUEST_ERROR, ...
> + }
> +}
> +
> +/**
> + * @brief Low-level slave-to-master transaction handler.
> + */
> +static uint8_t lsm303dlhc_mag_recv(I2CSlave *i2c)
> +{
> + LSM303DLHC_Mag_State *s = LSM303DLHC_MAG(i2c);
> +
> + DPRINTK("M<-S: 0x%02x (byte = %d)\n", s->buf[s->len], s->len);
> +
> + if (s->len < 6) {
> + return s->buf[s->len++];
> + } else {
> + return 0xff;
> + }
> +}
> +
> +/**
> + * @brief Low-level master-to-slave transaction handler.
> + */
> +static int lsm303dlhc_mag_send(I2CSlave *i2c, uint8_t data)
> +{
> + LSM303DLHC_Mag_State *s = LSM303DLHC_MAG(i2c);
> +
> + if (s->len == 0) {
> + /* First byte is the reg pointer */
> + DPRINTK("M->S: Setting reg pointer to 0x%02x\n", data);
> + s->pointer = data;
> + s->len++;
> + } else if (s->len == 1) {
> + /* Second byte is the new register value. */
> + DPRINTK("M->S: Setting reg 0x%02x to 0x%02x\n", s->pointer, data);
> + s->buf[0] = data;
> + lsm303dlhc_mag_write(s);
} else {
g_assert_not_reached();
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * @brief Bus state change handler.
> + */
> +static int lsm303dlhc_mag_event(I2CSlave *i2c, enum i2c_event event)
> +{
> + LSM303DLHC_Mag_State *s = LSM303DLHC_MAG(i2c);
> +
> + switch (event) {
> + case I2C_START_SEND:
> + DPRINTK("Event: START_SEND\n");
> + break;
> + case I2C_START_RECV:
> + DPRINTK("Event: START_RECV\n");
> + lsm303dlhc_mag_read(s);
> + break;
> + case I2C_FINISH:
> + DPRINTK("Event: FINISH\n");
> + break;
> + case I2C_NACK:
> + DPRINTK("Event: NACK\n");
> + break;
> + }
> +
> + s->len = 0;
> + return 0;
> +}
> +
> +/**
> + * @brief Device data description using VMSTATE macros.
> + */
> +static const VMStateDescription vmstate_lsm303dlhc_mag = {
> + .name = "LSM303DLHC_MAG",
> + .version_id = 0,
> + .minimum_version_id = 0,
> + .fields = (VMStateField[]) {
> +
> + VMSTATE_I2C_SLAVE(parent_obj, LSM303DLHC_Mag_State),
> + VMSTATE_UINT8(len, LSM303DLHC_Mag_State),
> + VMSTATE_UINT8_ARRAY(buf, LSM303DLHC_Mag_State, 6),
> + VMSTATE_UINT8(pointer, LSM303DLHC_Mag_State),
> + VMSTATE_UINT8(cra, LSM303DLHC_Mag_State),
> + VMSTATE_UINT8(crb, LSM303DLHC_Mag_State),
> + VMSTATE_UINT8(mr, LSM303DLHC_Mag_State),
> + VMSTATE_INT16(x, LSM303DLHC_Mag_State),
> + VMSTATE_INT16(z, LSM303DLHC_Mag_State),
> + VMSTATE_INT16(y, LSM303DLHC_Mag_State),
> + VMSTATE_UINT8(sr, LSM303DLHC_Mag_State),
> + VMSTATE_UINT8(ira, LSM303DLHC_Mag_State),
> + VMSTATE_UINT8(irb, LSM303DLHC_Mag_State),
> + VMSTATE_UINT8(irc, LSM303DLHC_Mag_State),
> + VMSTATE_INT16(temperature, LSM303DLHC_Mag_State),
> + VMSTATE_END_OF_LIST()
> + }
> +};
> +
> +/**
> + * @brief Put the device into post-reset default state.
> + */
> +static void lsm303dlhc_mag_reset(I2CSlave *i2c)
> +{
> + LSM303DLHC_Mag_State *s = LSM303DLHC_MAG(i2c);
> +
> + s->len = 0;
> + s->pointer = 0; /* Current register. */
> + s->buf[0] = 0;
> + s->buf[1] = 0;
> + s->buf[2] = 0;
> + s->buf[3] = 0;
> + s->buf[4] = 0;
> + s->buf[5] = 0;
memset(s->buf, 0, sizeof(s->buf));
> +
> + s->cra = 0x08; /* Temp Enabled = 0, Data Rate = 3.0 Hz. */
> + s->crb = 0x20; /* Gain = +/- 1.3 Guas. */
> + s->mr = 0x1; /* Operating Mode = Single conversion. */
> + s->x = 0;
> + s->z = 0;
> + s->y = 0;
> + s->sr = 0x1; /* DRDY = 1. */
> + s->ira = 0x48;
> + s->irb = 0x34;
> + s->irc = 0x33;
> + s->temperature = 0;
I'm unsure about this default value.
> +}
> +
> +/**
> + * @brief Callback handler when DeviceState 'realized' is set to true.
> + */
> +static void lsm303dlhc_mag_realize(DeviceState *dev, Error **errp)
Rather add a DeviceReset handler with the same content.
> +{
> + I2CSlave *i2c = I2C_SLAVE(dev);
> + LSM303DLHC_Mag_State *s = LSM303DLHC_MAG(i2c);
> +
> + /* Set the device into is default reset state. */
> + lsm303dlhc_mag_reset(&s->parent_obj);> +}
Regards,
Phil.
