Re: [Qemu-devel] [PATCH 11/14] timer: generalize ds1338

[David Gibson]

On Thu, Jul 05, 2018 at 11:19:58AM -0700, Michael Davidsaver wrote:
> Add class level handling for address space size
> and control register.
> 
> Signed-off-by: Michael Davidsaver <address@hidden>

Reviewed-by: David Gibson <address@hidden>

Although I don't love the name "addr_size" - just "nvram_size" seems
clearer.

> ---
>  hw/timer/ds-rtc.c | 62 
> +++++++++++++++++++++++++++++++++++++++++++------------
>  1 file changed, 49 insertions(+), 13 deletions(-)
> 
> diff --git a/hw/timer/ds-rtc.c b/hw/timer/ds-rtc.c
> index 126566ce1f..6d3a8b5586 100644
> --- a/hw/timer/ds-rtc.c
> +++ b/hw/timer/ds-rtc.c
> @@ -21,8 +21,10 @@
>   */
>  #define NVRAM_SIZE 64
>  
> -#define TYPE_DSRTC "ds1338"
> +#define TYPE_DSRTC "dsrtc"
>  #define DSRTC(obj) OBJECT_CHECK(DSRTCState, (obj), TYPE_DSRTC)
> +#define DSRTC_CLASS(klass) OBJECT_CLASS_CHECK(DSRTCClass, (klass), 
> TYPE_DSRTC)
> +#define DSRTC_GET_CLASS(obj) OBJECT_GET_CLASS(DSRTCClass, (obj), TYPE_DSRTC)
>  
>  /* values stored in BCD */
>  /* 00-59 */
> @@ -38,7 +40,7 @@
>  /* 0-99 */
>  #define R_YEAR  (0x6)
>  
> -#define R_CTRL  (0x7)
> +#define R_DS1338_CTRL (0x7)
>  
>  /* use 12 hour mode when set */
>  FIELD(HOUR, SET12, 6, 1)
> @@ -65,6 +67,15 @@ typedef struct DSRTCState {
>      bool addr_byte;
>  } DSRTCState;
>  
> +typedef struct DSRTCClass {
> +    I2CSlaveClass parent_obj;
> +
> +    /* actual address space size must be <= NVRAM_SIZE */
> +    unsigned addr_size;
> +    unsigned ctrl_offset;
> +    void (*ctrl_write)(DSRTCState *s, uint8_t);
> +} DSRTCClass;
> +
>  static const VMStateDescription vmstate_dsrtc = {
>      .name = "ds1338",
>      .version_id = 2,
> @@ -119,11 +130,12 @@ static void capture_current_time(DSRTCState *s)
>  
>  static void inc_regptr(DSRTCState *s)
>  {
> -    /* The register pointer wraps around after 0x3F; wraparound
> +    DSRTCClass *k = DSRTC_GET_CLASS(s);
> +    /* The register pointer wraps around after k->addr_size-1; wraparound
>       * causes the current time/date to be retransferred into
>       * the secondary registers.
>       */
> -    s->ptr = (s->ptr + 1) & (NVRAM_SIZE - 1);
> +    s->ptr = (s->ptr + 1) % k->addr_size;
>      if (!s->ptr) {
>          capture_current_time(s);
>      }
> @@ -205,20 +217,15 @@ static void dsrtc_update(DSRTCState *s)
>  static int dsrtc_send(I2CSlave *i2c, uint8_t data)
>  {
>      DSRTCState *s = DSRTC(i2c);
> +    DSRTCClass *k = DSRTC_GET_CLASS(s);
>  
>      if (s->addr_byte) {
> -        s->ptr = data & (NVRAM_SIZE - 1);
> +        s->ptr = data % k->addr_size;
>          s->addr_byte = false;
>          return 0;
>      }
> -    if (s->ptr == R_CTRL) {
> -        /* Control register. */
> -
> -        /* Allow guest to set no-op controls for clock out pin and
> -         * rate select.  Ignore write 1 to clear OSF.  We don't model
> -         * oscillator stop, so it is never set.
> -         */
> -        data = data & 0x93;
> +    if (s->ptr == k->ctrl_offset) {
> +        (k->ctrl_write)(s, data);
>      }
>      s->nvram[s->ptr] = data;
>      if (s->ptr <= R_YEAR) {
> @@ -253,15 +260,44 @@ static void dsrtc_class_init(ObjectClass *klass, void 
> *data)
>  }
>  
>  static const TypeInfo dsrtc_info = {
> +    .abstract      = true,
>      .name          = TYPE_DSRTC,
>      .parent        = TYPE_I2C_SLAVE,
>      .instance_size = sizeof(DSRTCState),
>      .class_init    = dsrtc_class_init,
>  };
>  
> +static void ds1338_control_write(DSRTCState *s, uint8_t data)
> +{
> +    /* Control register. */
> +
> +    /* Allow guest to set no-op controls for clock out pin and
> +     * rate select.  Ignore write 1 to clear OSF.  We don't model
> +     * oscillator stop, so it is never set.
> +     */
> +    s->nvram[R_DS1338_CTRL] = data & 0x93;
> +}
> +
> +static void ds1338_class_init(ObjectClass *klass, void *data)
> +{
> +    DSRTCClass *k = DSRTC_CLASS(klass);
> +
> +    k->addr_size = 0x40;
> +    k->ctrl_offset = R_DS1338_CTRL;
> +    k->ctrl_write = ds1338_control_write;
> +}
> +
> +static const TypeInfo ds1338_info = {
> +    .name          = "ds1338",
> +    .parent        = TYPE_DSRTC,
> +    .class_size    = sizeof(DSRTCClass),
> +    .class_init    = ds1338_class_init,
> +};
> +
>  static void dsrtc_register_types(void)
>  {
>      type_register_static(&dsrtc_info);
> +    type_register_static(&ds1338_info);
>  }
>  
>  type_init(dsrtc_register_types)

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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