Re: [PATCH v5 6/9] hw/misc/pca9552: Trace GPIO High/Low events

["Cédric Le Goater" <clg@kaod.org>]

On 6/22/20 8:34 PM, Philippe Mathieu-Daudé wrote:
> Add a trivial representation of the PCA9552 GPIOs.
> 
> Example booting obmc-phosphor-image:
> 
>   $ qemu-system-arm -M witherspoon-bmc -trace pca955x_gpio_status
>   1592689902.327837:pca955x_gpio_status pca-unspecified GPIOs 0-15 [*...............]
>   1592689902.329934:pca955x_gpio_status pca-unspecified GPIOs 0-15 [**..............]
>   1592689902.330717:pca955x_gpio_status pca-unspecified GPIOs 0-15 [***.............]
>   1592689902.331431:pca955x_gpio_status pca-unspecified GPIOs 0-15 [****............]
>   1592689902.332163:pca955x_gpio_status pca-unspecified GPIOs 0-15 [****.........*..]
>   1592689902.332888:pca955x_gpio_status pca-unspecified GPIOs 0-15 [****.........**.]
>   1592689902.333629:pca955x_gpio_status pca-unspecified GPIOs 0-15 [****.........***]
>   1592690032.793289:pca955x_gpio_status pca-unspecified GPIOs 0-15 [****.........*.*]
>   1592690033.303163:pca955x_gpio_status pca-unspecified GPIOs 0-15 [****.........***]
>   1592690033.812962:pca955x_gpio_status pca-unspecified GPIOs 0-15 [****.........*.*]
>   1592690034.323234:pca955x_gpio_status pca-unspecified GPIOs 0-15 [****.........***]
>   1592690034.832922:pca955x_gpio_status pca-unspecified GPIOs 0-15 [****.........*.*]
> 
> We notice the GPIO #14 (front-power LED) starts to blink.
> 
> This LED is described in the witherspoon device-tree [*]:
> 
>   front-power {
>       retain-state-shutdown;
>       default-state = "keep";
>       gpios = <&pca0 14 GPIO_ACTIVE_LOW>;
>   };
> 
> [*] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/aspeed-bmc-opp-witherspoon.dts?id=b1f9be9392f0#n140
> 
> Suggested-by: Cédric Le Goater <clg@kaod.org>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

Reviewed-by: Cédric Le Goater <clg@kaod.org>


> ---
>  hw/misc/pca9552.c    | 39 +++++++++++++++++++++++++++++++++++++++
>  hw/misc/trace-events |  3 +++
>  2 files changed, 42 insertions(+)
> 
> diff --git a/hw/misc/pca9552.c b/hw/misc/pca9552.c
> index d6d84c6451..13f5ed0da4 100644
> --- a/hw/misc/pca9552.c
> +++ b/hw/misc/pca9552.c
> @@ -13,12 +13,14 @@
>  #include "qemu/osdep.h"
>  #include "qemu/log.h"
>  #include "qemu/module.h"
> +#include "qemu/bitops.h"
>  #include "hw/qdev-properties.h"
>  #include "hw/misc/pca9552.h"
>  #include "hw/misc/pca9552_regs.h"
>  #include "migration/vmstate.h"
>  #include "qapi/error.h"
>  #include "qapi/visitor.h"
> +#include "trace.h"
>  
>  typedef struct PCA955xClass {
>      /*< private >*/
> @@ -49,6 +51,39 @@ static uint8_t pca955x_pin_get_config(PCA955xState *s, int pin)
>      return extract32(s->regs[reg], shift, 2);
>  }
>  
> +/* Return INPUT status (bit #N belongs to GPIO #N) */
> +static uint16_t pca955x_pins_get_status(PCA955xState *s)
> +{
> +    return (s->regs[PCA9552_INPUT1] << 8) | s->regs[PCA9552_INPUT0];
> +}
> +
> +static void pca955x_display_pins_status(PCA955xState *s,
> +                                        uint16_t previous_pins_status)
> +{
> +    PCA955xClass *k = PCA955X_GET_CLASS(s);
> +    uint16_t pins_status, pins_changed;
> +    int i;
> +
> +    pins_status = pca955x_pins_get_status(s);
> +    pins_changed = previous_pins_status ^ pins_status;
> +    if (!pins_changed) {
> +        return;
> +    }
> +    if (trace_event_get_state_backends(TRACE_PCA955X_GPIO_STATUS)) {
> +        char *buf = g_newa(char, k->pin_count + 1);
> +
> +        for (i = 0; i < k->pin_count; i++) {
> +            if (extract32(pins_status, i, 1)) {
> +                buf[i] = '*';
> +            } else {
> +                buf[i] = '.';
> +            }
> +        }
> +        buf[i] = '\0';
> +        trace_pca955x_gpio_status(s->description, buf);
> +    }
> +}
> +
>  static void pca955x_update_pin_input(PCA955xState *s)
>  {
>      PCA955xClass *k = PCA955X_GET_CLASS(s);
> @@ -98,6 +133,8 @@ static uint8_t pca955x_read(PCA955xState *s, uint8_t reg)
>  
>  static void pca955x_write(PCA955xState *s, uint8_t reg, uint8_t data)
>  {
> +    uint16_t pins_status;
> +
>      switch (reg) {
>      case PCA9552_PSC0:
>      case PCA9552_PWM0:
> @@ -110,8 +147,10 @@ static void pca955x_write(PCA955xState *s, uint8_t reg, uint8_t data)
>      case PCA9552_LS1:
>      case PCA9552_LS2:
>      case PCA9552_LS3:
> +        pins_status = pca955x_pins_get_status(s);
>          s->regs[reg] = data;
>          pca955x_update_pin_input(s);
> +        pca955x_display_pins_status(s, pins_status);
>          break;
>  
>      case PCA9552_INPUT0:
> diff --git a/hw/misc/trace-events b/hw/misc/trace-events
> index 5561746866..9282c60dd9 100644
> --- a/hw/misc/trace-events
> +++ b/hw/misc/trace-events
> @@ -206,3 +206,6 @@ via1_rtc_cmd_pram_sect_write(int sector, int offset, int addr, int value) "secto
>  # grlib_ahb_apb_pnp.c
>  grlib_ahb_pnp_read(uint64_t addr, uint32_t value) "AHB PnP read addr:0x%03"PRIx64" data:0x%08x"
>  grlib_apb_pnp_read(uint64_t addr, uint32_t value) "APB PnP read addr:0x%03"PRIx64" data:0x%08x"
> +
> +# pca9552.c
> +pca955x_gpio_status(const char *description, const char *buf) "%s GPIOs 0-15 [%s]"
>