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

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Cédric Le Goater (clg@kaod.org) wrote:
> 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 ? 

I don't think so; there were some other people implementing
similar patches; it got bogged down in the question of string visitors
and I hadn't dug to see if that's got fixed in the last 3 years.

Dave


> > Signed-off-by: Joel Stanley <joel@jms.id.au>
> 
> 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 <joel@jms.id.au>
> > ---
> >  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)
> > 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK