On Sun, 15 Aug 2021 at 17:31, Kevin Townsend <kevin.towns...@linaro.org> 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 > mag_x, mag_y and mag_z properties, as well as the 12-bit > temperature output via the temperature property. > > Signed-off-by: Kevin Townsend <kevin.towns...@linaro.org>
Hi; thanks for this patch. I have some code review comments below. > --- > hw/sensor/Kconfig | 4 + > hw/sensor/lsm303dlhc_mag.c | 502 +++++++++++++++++++++++++++++++++++++ > hw/sensor/meson.build | 1 + > 3 files changed, 507 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 Should have the newline. > diff --git a/hw/sensor/lsm303dlhc_mag.c b/hw/sensor/lsm303dlhc_mag.c > new file mode 100644 > index 0000000000..009b6dae6b > --- /dev/null > +++ b/hw/sensor/lsm303dlhc_mag.c > @@ -0,0 +1,502 @@ > +/* > + * LSM303DLHC I2C magnetometer. > + * > + * Copyright (C) 2021 Linaro Ltd. > + * Written by Kevin Townsend <kevin.towns...@linaro.org> > + * > + * SPDX-License-Identifier: GPL-2.0-or-later You could add the URL of the datasheet here: https://www.st.com/resource/en/datasheet/lsm303dlhc.pdf > + */ > + > +/* > + * 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" > +#include "qemu/log.h" > +#include "qemu/bswap.h" > + > +/* 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") Is this kind of #define for property names something you've borrowed from elsewhere in the codebase? > +enum LSM303DLHC_Mag_Reg { Our naming convention doesn't have underscores in type names generally; we prefer CamelCase for those. (Some older code uses different style.) > + 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 > +}; So if I'm reading the datasheet correctly, the LM303DLHC is really two completely distinct i2c devices in a single package with different slave addresses; this QEMU device implements only the magnetometer i2c device, and if we wanted to add the accelerometer device we'd implement that as a second separate QEMU i2c device ? > + > +typedef struct LSM303DLHC_Mag_State { Again, CamelCase. > + I2CSlave parent_obj; > + > + uint8_t cra; > + uint8_t crb; > + uint8_t mr; > + > + /** > + * @brief X-axis register value in LSB. Exact relationship to gauss > + * varies depending on the current gain settings. > + */ This @brief stuff isn't how we do doc comments. For a simple internal to the device struct like this you don't really need to mark it up as a doc comment at all; just use a normal block comment (you could combine these 3 comments, since they're saying the same thing). > + int16_t x; > + > + /** > + * @brief Z-axis register value in LSB. Exact relationship to gauss > + * varies depending on the current gain settings. > + */ > + int16_t z; > + > + /** > + * @brief Y-axis register value in LSB. Exact relationship to gauss > + * varies depending on the current gain settings. > + */ > + int16_t y; > + > + uint8_t sr; > + uint8_t ira; > + uint8_t irb; > + uint8_t irc; > + > + /** > + * @brief Temperature in LSB where 1 degree C = 8 lsb. > + */ > + int16_t temperature; > + > + uint8_t len; > + uint8_t buf[6]; > + uint8_t pointer; > +} LSM303DLHC_Mag_State; > + > +#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. > + */ For a file-internal static function, doc comment formatting is optional (we only really want it for functions declared in header files). I would just provide a normal comment here. (If you do want a doc-comment, QEMU's format for that is not this @brief style; bitops.h has some examples of what we do, which is more or less Linux kernel kerneldoc format.) > +static void lsm303dlhc_mag_get_xyz(Object *obj, Visitor *v, const char *name, > + void *opaque, Error **errp) > +{ > + 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); > +} I think you'd be better off defining different get/set functions for x,y,z rather than sharing them and then having to do a bunch of strcmps on the property name to split them apart again. > + > +/** > + * @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 value; > + > + if (!visit_type_int(v, name, &value, errp)) { > + return; > + } > + > + if (value > 2047 || value < -2048) { > + error_setg(errp, "value %d lsb is out of range", value); Why "lsb" ? > + return; > + } > + > + if (strcmp(name, LSM303DLHC_MSG_PROP_MAGX) == 0) { > + s->x = (int16_t)value; > + } else if (strcmp(name, LSM303DLHC_MSG_PROP_MAGY) == 0) { > + s->y = (int16_t)value; > + } else if (strcmp(name, LSM303DLHC_MSG_PROP_MAGZ) == 0) { > + s->z = (int16_t)value; > + } 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 value; > + > + if (!visit_type_int(v, name, &value, errp)) { > + return; > + } > + > + if (value > 2047 || value < -2048) { > + error_setg(errp, "value %d lsb is out of range", value); > + return; > + } > + > + s->temperature = (int16_t)value; > +} > + > +/** > + * @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. How hard would it be to implement the behaviour correctly for all cases? I find it's usually better to model something correctly from the start: usually the person writing the code knows the h/w behaviour better than anybody else coming along later trying to figure out why some other guest code doesn't work on the model... > + */ > + > + 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: > + stw_be_p(s->buf, s->x); > + s->len += sizeof(s->x); > + stw_be_p(s->buf + 2, s->z); > + s->len += sizeof(s->z); > + stw_be_p(s->buf + 4, s->y); > + s->len += sizeof(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: > + /* Check if the temperature sensor is enabled of not (CRA & 0x80). */ "or not" > + if (s->cra & 0x80) { > + 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) > +{ > + 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, "reg is read-only: 0x%02X", > s->buf[0]); > + break; > + } > +} > + > +/** > + * @brief Low-level slave-to-master transaction handler. > + */ > +static uint8_t lsm303dlhc_mag_recv(I2CSlave *i2c) > +{ > + LSM303DLHC_Mag_State *s = LSM303DLHC_MAG(i2c); > + > + 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 */ > + s->pointer = data; > + s->len++; > + } else if (s->len == 1) { > + /* Second byte is the new register value. */ > + 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: > + break; > + case I2C_START_RECV: > + lsm303dlhc_mag_read(s); > + break; > + case I2C_FINISH: > + break; > + case I2C_NACK: > + 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_default_cfg(I2CSlave *i2c) > +{ > + LSM303DLHC_Mag_State *s = LSM303DLHC_MAG(i2c); > + > + /* Set the device into is default reset state. */ > + s->len = 0; > + s->pointer = 0; /* Current register. */ > + 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. */ "gauss" ? > + s->mr = 0x1; /* Operating Mode = Single conversion. */ > + s->x = 0; > + s->z = 0; > + s->y = 0; > + s->sr = 0x1; /* DRDY = 1. */ Do you understand how the DRDY and LOCK bits work ? The datasheet is unclear. Also, what's the difference between "single-conversion" and "continuous-conversion" modes ? > + s->ira = 0x48; > + s->irb = 0x34; > + s->irc = 0x33; > + s->temperature = 0; /* Default to 0 degrees C (0/8 lsb = 0 C). */ > +} > + > +/** > + * @brief Callback handler when DeviceState 'reset' is set to true. > + */ > +static void lsm303dlhc_mag_reset(DeviceState *dev) > +{ > + I2CSlave *i2c = I2C_SLAVE(dev); > + LSM303DLHC_Mag_State *s = LSM303DLHC_MAG(i2c); > + > + /* Set the device into is default reset state. */ > + lsm303dlhc_mag_default_cfg(&s->parent_obj); Misindentation. Also, don't use the parent_obj field; always use the QOM cast macro when you need the pointer to something as a different type. In this case you already have the I2CSlave*, in 'i2c'. But better would be to make lsm303dlhc_mag_default_cfg() take a LSM303DLHC_Mag_State* directly rather than taking an I2CSlave* and casting it internally. > +} > + > +/** > + * @brief Initialisation of any public properties. > + * > + * @note Properties are an object's external interface, and are set before > the > + * object is started. The 'temperature' property here enables the > + * temperature registers to be set by the host OS, for example, or via > + * the QEMU monitor interface using commands like 'qom-set' and > 'qom-get'. > + */ You don't need to say that kind of thing, you can assume the reader knows what properties are. > +static void lsm303dlhc_mag_initfn(Object *obj) > +{ > + object_property_add(obj, LSM303DLHC_MSG_PROP_MAGX, "int", > + lsm303dlhc_mag_get_xyz, > + lsm303dlhc_mag_set_xyz, NULL, NULL); > + > + object_property_add(obj, LSM303DLHC_MSG_PROP_MAGY, "int", > + lsm303dlhc_mag_get_xyz, > + lsm303dlhc_mag_set_xyz, NULL, NULL); > + > + object_property_add(obj, LSM303DLHC_MSG_PROP_MAGZ, "int", > + lsm303dlhc_mag_get_xyz, > + lsm303dlhc_mag_set_xyz, NULL, NULL); What units are these in? It looks like your implementation just uses the property values as the raw -2048..+2048 value that the X/Y/Z registers read as. Would it be better for the properties to set the value in Gauss, and then the model to honour the gain settings in CRB_REG_M.GN{0,1,2} ? That way guest code that adjusts the gain will get the results it is expecting. > + > + object_property_add(obj, LSM303DLHC_MSG_PROP_TEMP, "int", > + lsm303dlhc_mag_get_temperature, > + lsm303dlhc_mag_set_temperature, NULL, NULL); What units is this in? > +} > + > +/** > + * @brief Set the virtual method pointers (bus state change, tx/rx, etc.). > + */ > +static void lsm303dlhc_mag_class_init(ObjectClass *klass, void *data) > +{ > + DeviceClass *dc = DEVICE_CLASS(klass); > + I2CSlaveClass *k = I2C_SLAVE_CLASS(klass); > + > + /* DeviceState 'reset' handler. */ > + dc->reset = lsm303dlhc_mag_reset; > + > + /* VM State description (device data). */ > + dc->vmsd = &vmstate_lsm303dlhc_mag; > + > + /* Bus state change handler. */ > + k->event = lsm303dlhc_mag_event; > + > + /* Slave to master handler. */ > + k->recv = lsm303dlhc_mag_recv; > + > + /* Master to slave handler. */ > + k->send = lsm303dlhc_mag_send; These comments are all kind of superfluous too. > +} > + > +static const TypeInfo lsm303dlhc_mag_info = { > + .name = TYPE_LSM303DLHC_MAG, > + .parent = TYPE_I2C_SLAVE, > + .instance_size = sizeof(LSM303DLHC_Mag_State), > + .instance_init = lsm303dlhc_mag_initfn, > + .class_init = lsm303dlhc_mag_class_init, > +}; > + > +static void lsm303dlhc_mag_register_types(void) > +{ > + type_register_static(&lsm303dlhc_mag_info); > +} > + > +type_init(lsm303dlhc_mag_register_types) > diff --git a/hw/sensor/meson.build b/hw/sensor/meson.build > index 034e3e0207..95406abd24 100644 > --- a/hw/sensor/meson.build > +++ b/hw/sensor/meson.build > @@ -3,3 +3,4 @@ softmmu_ss.add(when: 'CONFIG_TMP421', if_true: > files('tmp421.c')) > softmmu_ss.add(when: 'CONFIG_EMC141X', if_true: files('emc141x.c')) > softmmu_ss.add(when: 'CONFIG_ADM1272', if_true: files('adm1272.c')) > softmmu_ss.add(when: 'CONFIG_MAX34451', if_true: files('max34451.c')) > +softmmu_ss.add(when: 'CONFIG_LSM303DLHC_MAG', if_true: > files('lsm303dlhc_mag.c')) You need also a stanza in hw/sensor/Kconfig, like this: config LSM303DLHC_MAG bool depends on I2C Also, unless the Kconfig for some board does 'select LSM303DLHC_MAG' I don't think this code will ever be compiled in... thanks -- PMM
