hw/misc: Add GPIOs for duty in NPCM7xx PWM

This patch adds GPIOs in NPCM7xx PWM module for its duty values.
The purpose of this is to connect it to the MFT module to provide
an input for measuring a PWM fan's RPM. Each PWM module has
NPCM7XX_PWM_PER_MODULE of GPIOs, each one corresponds to
one PWM instance and can connect to multiple fan instances in MFT.

Reviewed-by: Doug Evans <dje@google.com>
Reviewed-by: Tyrone Ting <kfting@nuvoton.com>
Signed-off-by: Hao Wu <wuhaotsh@google.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20210311180855.149764-2-wuhaotsh@google.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/misc/npcm7xx_pwm.c

@@ -139,6 +139,7 @@ static void npcm7xx_pwm_update_duty(NPCM7xxPWM *p)
         trace_npcm7xx_pwm_update_duty(DEVICE(p->module)->canonical_path,
                                       p->index, p->duty, duty);
         p->duty = duty;
+        qemu_set_irq(p->module->duty_gpio_out[p->index], p->duty);
     }
 }
 
@@ -483,6 +484,7 @@ static void npcm7xx_pwm_init(Object *obj)
     SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
     int i;
 
+    QEMU_BUILD_BUG_ON(ARRAY_SIZE(s->pwm) != NPCM7XX_PWM_PER_MODULE);
     for (i = 0; i < NPCM7XX_PWM_PER_MODULE; i++) {
         NPCM7xxPWM *p = &s->pwm[i];
         p->module = s;
@@ -501,6 +503,8 @@ static void npcm7xx_pwm_init(Object *obj)
         object_property_add_uint32_ptr(obj, "duty[*]",
                 &s->pwm[i].duty, OBJ_PROP_FLAG_READ);
     }
+    qdev_init_gpio_out_named(DEVICE(s), s->duty_gpio_out,
+                             "duty-gpio-out", NPCM7XX_PWM_PER_MODULE);
 }
 
 static const VMStateDescription vmstate_npcm7xx_pwm = {

include/hw/misc/npcm7xx_pwm.h

@@ -77,6 +77,7 @@ typedef struct NPCM7xxPWM {
  * @iomem: Memory region through which registers are accessed.
  * @clock: The PWM clock.
  * @pwm: The PWM channels owned by this module.
+ * @duty_gpio_out: The duty cycle of each PWM channels as a output GPIO.
  * @ppr: The prescaler register.
  * @csr: The clock selector register.
  * @pcr: The control register.
@@ -89,7 +90,8 @@ struct NPCM7xxPWMState {
     MemoryRegion iomem;
 
     Clock       *clock;
-    NPCM7xxPWM pwm[NPCM7XX_PWM_PER_MODULE];
+    NPCM7xxPWM  pwm[NPCM7XX_PWM_PER_MODULE];
+    qemu_irq    duty_gpio_out[NPCM7XX_PWM_PER_MODULE];
 
     uint32_t    ppr;
     uint32_t    csr;