rt1718s: implement adc read

Cherry uses the VBUS1 adc channel in RT1718S to check the VBUS voltage
on port 1. Thus add this function for Cherry.

BUG=b:196001868
TEST=1) manually check the readings of ADC_VBUS1
     2) Combined with board/ side changes, `ectool usbpdpower` shows
        correct value
BRANCH=main

Signed-off-by: Ting Shen <phoenixshen@google.com>
Change-Id: I243f28b2bd4e8541257afcacb50a024a72e301fd
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3040801
Reviewed-by: Sue Chen <sue.chen@quanta.corp-partner.google.com>
Reviewed-by: Eric Yilun Lin <yllin@google.com>
Tested-by: Sue Chen <sue.chen@quanta.corp-partner.google.com>
Tested-by: Ting Shen <phoenixshen@chromium.org>
Commit-Queue: Ting Shen <phoenixshen@chromium.org>

1 files changed, 94 insertions, 6 deletions

diff --git a/driver/tcpm/rt1718s.c b/driver/tcpm/rt1718s.c
index 631d98a522..96a08785c2 100644
--- a/driver/tcpm/rt1718s.c
+++ b/driver/tcpm/rt1718s.c
@@ -25,26 +25,42 @@
 #define RT1718S_SW_RESET_DELAY_MS 2
 
 /* i2c_write function which won't wake TCPC from low power mode. */
-int rt1718s_write8(int port, int reg, int val)
+static int rt1718s_write(int port, int reg, int val, int len)
 {
 	if (reg > 0xFF) {
 		return i2c_write_offset16(
 			tcpc_config[port].i2c_info.port,
 			tcpc_config[port].i2c_info.addr_flags,
-			reg, val, 1);
+			reg, val, len);
+	} else if (len == 1) {
+		return tcpc_write(port, reg, val);
+	} else {
+		return tcpc_write16(port, reg, val);
 	}
-	return tcpc_write(port, reg, val);
 }
 
-int rt1718s_read8(int port, int reg, int *val)
+static int rt1718s_read(int port, int reg, int *val, int len)
 {
 	if (reg > 0xFF) {
 		return i2c_read_offset16(
 			tcpc_config[port].i2c_info.port,
 			tcpc_config[port].i2c_info.addr_flags,
-			reg, val, 1);
+			reg, val, len);
+	} else if (len == 1) {
+		return tcpc_read(port, reg, val);
+	} else {
+		return tcpc_read16(port, reg, val);
 	}
-	return tcpc_read(port, reg, val);
+}
+
+int rt1718s_write8(int port, int reg, int val)
+{
+	return rt1718s_write(port, reg, val, 1);
+}
+
+int rt1718s_read8(int port, int reg, int *val)
+{
+	return rt1718s_read(port, reg, val, 1);
 }
 
 int rt1718s_update_bits8(int port, int reg, int mask, int val)
@@ -61,6 +77,17 @@ int rt1718s_update_bits8(int port, int reg, int mask, int val)
 	return rt1718s_write8(port, reg, reg_val);
 }
 
+int rt1718s_write16(int port, int reg, int val)
+{
+	return rt1718s_write(port, reg, val, 2);
+}
+
+int rt1718s_read16(int port, int reg, int *val)
+{
+	return rt1718s_read(port, reg, val, 2);
+}
+
+
 static int rt1718s_sw_reset(int port)
 {
 	int rv;
@@ -385,6 +412,67 @@ static int rt1718s_enter_low_power_mode(int port)
 }
 #endif
 
+int rt1718s_get_adc(int port, enum rt1718s_adc_channel channel, int *adc_val)
+{
+	static struct mutex adc_lock;
+	int rv;
+	const int max_wait_times = 30;
+
+	if (in_interrupt_context()) {
+		CPRINTS("Err: use ADC in IRQ");
+		return EC_ERROR_INVAL;
+	}
+
+	mutex_lock(&adc_lock);
+
+	/* Start ADC conversation */
+	rv = rt1718s_write16(port, RT1718S_ADC_CTRL_01, BIT(channel));
+	if (rv)
+		goto out;
+
+	/*
+	 * The expected conversion time is 85.3us * number of enabled channels.
+	 * Polling for 3ms should be long enough.
+	 */
+	for (int i = 0; i < max_wait_times; i++) {
+		int adc_done;
+
+		usleep(100);
+		rv = rt1718s_read8(port, RT1718S_RT_INT6, &adc_done);
+		if (rv)
+			goto out;
+		if (adc_done & RT1718S_RT_INT6_INT_ADC_DONE)
+			break;
+		if (i == max_wait_times - 1) {
+			CPRINTS("conversion fail channel=%d", channel);
+			rv = EC_ERROR_TIMEOUT;
+			goto out;
+		}
+	}
+
+	/* Read ADC data */
+	rv = rt1718s_read16(port, RT1718S_ADC_CHX_VOL_L(channel), adc_val);
+	if (rv)
+		goto out;
+
+	/*
+	 * The resolution of VBUS1 ADC is 12.5mV,
+	 * other channels are 4mV.
+	 */
+	if (channel == RT1718S_ADC_VBUS1)
+		*adc_val = *adc_val * 125 / 10;
+	else
+		*adc_val *= 4;
+
+out:
+	/* Cleanup: disable adc and clear interrupt. Error ignored. */
+	rt1718s_write16(port, RT1718S_ADC_CTRL_01, 0);
+	rt1718s_write8(port, RT1718S_RT_INT6, RT1718S_RT_INT6_INT_ADC_DONE);
+
+	mutex_unlock(&adc_lock);
+	return rv;
+}
+
 /* RT1718S is a TCPCI compatible port controller */
 const struct tcpm_drv rt1718s_tcpm_drv = {
 	.init			= &rt1718s_init,