Re: [PATCH] misc/pca9552: Add qom set and get

[Cédric Le Goater]

On 18/11/2019 07:17, Joel Stanley wrote:
> Following the pattern of the work recently done with the ASPEED GPIO
> model, this adds support for inspecting and modifying the PCA9552 LEDs
> from the monitor.
> 
>  (qemu) qom-set  /machine/unattached/device[17] led0 on
>  (qemu) qom-get  /machine/unattached/device[17] led0
>  "on"
> 
>  (qemu) qom-set  /machine/unattached/device[17] led0 off
>  (qemu) qom-get  /machine/unattached/device[17] led0
>  "off"
> 
>  (qemu) qom-set  /machine/unattached/device[17] led0 pwm0
>  (qemu) qom-get  /machine/unattached/device[17] led0
>  "pwm0"
> 
>  (qemu) qom-set  /machine/unattached/device[17] led0 pwm1
>  (qemu) qom-get  /machine/unattached/device[17] led0
>  "pwm1"

It would be nice to revive the QOM get patchset from David. 

        http://patchwork.ozlabs.org/patch/666458/

Did we reach some consensus ? 

> Signed-off-by: Joel Stanley <address@hidden>

Some comments below.

> ---
> The qom device in mainline qemu is a different path. Using the monitor
> examine `info qom-tree /machine/unattached/` to discover it.
> 
> This can be tested with a Witherspoon image.
> 
> $ wget 
> https://openpower.xyz/job/openbmc-build/distro=ubuntu,label=builder,target=witherspoon/lastSuccessfulBuild/artifact/deploy/images/witherspoon/obmc-phosphor-image-witherspoon.ubi.mtd
> 
> $ qemu-system-arm -M witherspoon-bmc -serial pty -monitor pty -nographic \
>  -drive file=obmc-phosphor-image-witherspoon.ubi.mtd,format=raw,if=mtd
> char device redirected to /dev/pts/5 (label compat_monitor0)
> char device redirected to /dev/pts/10 (label serial0)
> 
> $ screen /dev/pts/5
> QEMU 4.1.91 monitor - type 'help' for more information
> (qemu) qom-get  /machine/unattached/device[17] led0
> "off"
> 
> $ screen /dev/pts/19
> root@witherspoon:~# cd /sys/class/gpio/
> root@witherspoon:/sys/class/gpio# echo 248 > export
> root@witherspoon:/sys/class/gpio# cat gpio248/value
> 0
> 
> (qemu) qom-set  /machine/unattached/device[17] led0 on
> 
> root@witherspoon:/sys/class/gpio# echo out > gpio248/direction
> root@witherspoon:/sys/class/gpio# cat gpio248/value
> 1
> 
> (qemu) qom-get  /machine/unattached/device[17] led0
> "on"
> 
> (qemu) qom-set  /machine/unattached/device[17] led0 off
> (qemu) qom-get  /machine/unattached/device[17] led0
> "off"
> 
> root@witherspoon:/sys/class/gpio# cat gpio248/value
> 0
> 
> Signed-off-by: Joel Stanley <address@hidden>
> ---
>  hw/misc/pca9552.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 91 insertions(+)
> 
> diff --git a/hw/misc/pca9552.c b/hw/misc/pca9552.c
> index 73be28d9369c..0362aac8c862 100644
> --- a/hw/misc/pca9552.c
> +++ b/hw/misc/pca9552.c
> @@ -15,12 +15,16 @@
>  #include "hw/misc/pca9552.h"
>  #include "hw/misc/pca9552_regs.h"
>  #include "migration/vmstate.h"
> +#include "qapi/error.h"
> +#include "qapi/visitor.h"
>  
>  #define PCA9552_LED_ON   0x0
>  #define PCA9552_LED_OFF  0x1
>  #define PCA9552_LED_PWM0 0x2
>  #define PCA9552_LED_PWM1 0x3
>  
> +static const char *led_state[] = {"on", "off", "pwm0", "pwm1"};
> +
>  static uint8_t pca9552_pin_get_config(PCA9552State *s, int pin)
>  {
>      uint8_t reg   = PCA9552_LS0 + (pin / 4);
> @@ -169,6 +173,84 @@ static int pca9552_event(I2CSlave *i2c, enum i2c_event 
> event)
>      return 0;
>  }
>  
> +static void pca9552_get_led(Object *obj, Visitor *v, const char *name,
> +                            void *opaque, Error **errp)
> +{
> +    PCA9552State *s = PCA9552(obj);
> +    int led, rc, reg;
> +    char *str;
> +    uint8_t state;
> +
> +    rc = sscanf(name, "led%2d", &led);
> +    if (rc != 1) {
> +        error_setg(errp, "%s: error reading %s", __func__, name);
> +        return;
> +    }
> +    if (led < 0 || led > s->nr_leds) {
> +        error_setg(errp, "%s invalid led %s", __func__, name);
> +        return;
> +    }
> +    /*
> +     * Get the LSx register as the qom interface should expose the device
> +     * state, not the modeled 'input line' behaviour which would come from
> +     * reading the INPUTx reg
> +     */
> +    reg = PCA9552_LS0 + led / 4;
> +    state = (pca9552_read(s, reg) >> (led % 8)) & 0x3;

Could we add accessors to extract the register fields and to clarify 
the layout ? 

> +    str = g_strdup(led_state[state]);
> +    visit_type_str(v, name, &str, errp);
> +}
> +
> +/*
> + * Return an LED selector register value based on an existing one, with
> + * the appropriate 2-bit state value set for the given LED number (0-3).
> + */
> +static inline uint8_t pca955x_ledsel(uint8_t oldval, int led_num, int state)
> +{
> +        return (oldval & (~(0x3 << (led_num << 1)))) |
> +                ((state & 0x3) << (led_num << 1));
> +}
> +
> +static void pca9552_set_led(Object *obj, Visitor *v, const char *name,
> +                            void *opaque, Error **errp)
> +{
> +    PCA9552State *s = PCA9552(obj);
> +    Error *local_err = NULL;
> +    int led, rc, reg, val;
> +    uint8_t state;
> +    char *state_str;
> +
> +    visit_type_str(v, name, &state_str, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
> +    }
> +    rc = sscanf(name, "led%2d", &led);
> +    if (rc != 1) {
> +        error_setg(errp, "%s: error reading %s", __func__, name);
> +        return;
> +    }
> +    if (led < 0 || led > s->nr_leds) {
> +        error_setg(errp, "%s invalid led %s", __func__, name);
> +        return;
> +    }
> +
> +    for (state = 0; state < ARRAY_SIZE(led_state); state++) {
> +        if (!strcmp(state_str, led_state[state])) {
> +            break;
> +        }
> +    }
> +    if (state >= ARRAY_SIZE(led_state)) {
> +        error_setg(errp, "%s invalid led state %s", __func__, state_str);
> +        return;
> +    }
> +
> +    reg = PCA9552_LS0 + led / 4;
> +    val = pca9552_read(s, reg);
> +    val = pca955x_ledsel(val, led % 4, state);
> +    pca9552_write(s, reg, val);
> +}
> +
>  static const VMStateDescription pca9552_vmstate = {
>      .name = "PCA9552",
>      .version_id = 0,
> @@ -204,6 +286,7 @@ static void pca9552_reset(DeviceState *dev)
>  static void pca9552_initfn(Object *obj)
>  {
>      PCA9552State *s = PCA9552(obj);
> +    int led;
>  
>      /* If support for the other PCA955X devices are implemented, these
>       * constant values might be part of class structure describing the
> @@ -211,6 +294,14 @@ static void pca9552_initfn(Object *obj)
>       */
>      s->max_reg = PCA9552_LS3;
>      s->nr_leds = 16;
> +
> +    for (led = 0; led < s->nr_leds; led++) {
> +        char *name;
> +
> +        name = g_strdup_printf("led%d", led);
> +        object_property_add(obj, name, "bool", pca9552_get_led, 
> pca9552_set_led,
> +                            NULL, NULL, NULL);

It misses a :

   g_free(name)

C.

> +    }
>  }
>  
>  static void pca9552_class_init(ObjectClass *klass, void *data)
>