zinger: minimuffin: add board support for minimuffin

Minimuffin is identical to zinger, same MCU, same gpio, same
circuitry aroundt the MCU with two differences:
- Rated current is 2.25A instead of 3A
- USB PD hardware device ID needs to be different so that host
can differentiate between the two.

Due to the similarity between the two, minimuffin is defined
as a symlink to the zinger board.

BUG=none
BRANCH=samus
TEST=make BOARD=minimuffin
load onto a zinger and verify that samus reads device ID correctly
and limits input current limit to 2.25mA.

Change-Id: Ie39ec43262c7d14663eb68abff073bfeec451a24
Signed-off-by: Alec Berg <alecaberg@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/220689
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

7 files changed, 32 insertions, 11 deletions

diff --git a/board/minimuffin b/board/minimuffin
new file mode 120000
index 0000000000..caf3ff6e0a
--- /dev/null
+++ b/board/minimuffin
@@ -0,0 +1 @@
+zinger/
\ No newline at end of file
diff --git a/board/zinger/board.h b/board/zinger/board.h
index 639991be33..daca59de8f 100644
--- a/board/zinger/board.h
+++ b/board/zinger/board.h
@@ -3,7 +3,10 @@
  * found in the LICENSE file.
  */
 
-/* Tiny charger configuration */
+/*
+ * Tiny charger configuration. This config is used for multiple boards
+ * including zinger and minimuffin.
+ */
 
 #ifndef __BOARD_H
 #define __BOARD_H
@@ -19,6 +22,7 @@
 #undef CONFIG_USB_PD_DUAL_ROLE
 #undef CONFIG_USB_PD_INTERNAL_COMP
 #define CONFIG_USB_PD_CUSTOM_VDM
+#undef CONFIG_USB_PD_RX_COMP_IRQ
 #define CONFIG_HW_CRC
 #define CONFIG_SHA1
 #undef CONFIG_WATCHDOG_HELP
@@ -43,7 +47,13 @@
 #define UARTN_BASE STM32_USART_BASE(CONFIG_UART_CONSOLE)
 
 /* USB PD ChromeOS VDM information */
+#if defined(BOARD_ZINGER)
 #define USB_PD_HARDWARE_DEVICE_ID 1
+#elif defined(BOARD_MINIMUFFIN)
+#define USB_PD_HARDWARE_DEVICE_ID 2
+#else
+#error "Board does not have a USB-PD HW Device ID"
+#endif
 
 #ifndef __ASSEMBLER__
 
diff --git a/board/zinger/usb_pd_policy.c b/board/zinger/usb_pd_policy.c
index 6ef6fee461..bc2a0ede3b 100644
--- a/board/zinger/usb_pd_policy.c
+++ b/board/zinger/usb_pd_policy.c
@@ -88,10 +88,17 @@ static timestamp_t fault_deadline;
 /* convert raw ADC value to mV */
 #define ADC_TO_VOLT_MV(vbus) ((vbus)*VOLT_DIV*VDDA_MV/ADC_SCALE)
 
-/* Max current : 20% over 3A = 3.6A */
-#define MAX_CURRENT VBUS_MA(3600)
-/* Fast short circuit protection : 4.5A */
-#define MAX_CURRENT_FAST VBUS_MA(4500)
+/* Max current */
+#if defined(BOARD_ZINGER)
+#define RATED_CURRENT 3000
+#elif defined(BOARD_MINIMUFFIN)
+#define RATED_CURRENT 2250
+#endif
+
+/* Max current : 20% over rated current */
+#define MAX_CURRENT VBUS_MA(RATED_CURRENT * 6/5)
+/* Fast short circuit protection : 50% over rated current */
+#define MAX_CURRENT_FAST VBUS_MA(RATED_CURRENT * 3/2)
 /* reset over-current after 1 second */
 #define OCP_TIMEOUT SECOND
 
@@ -143,9 +150,9 @@ static void discharge_voltage(int target_volt)
 /* Power Delivery Objects */
 const uint32_t pd_src_pdo[] = {
 		PDO_FIXED(5000,   500, PDO_FIXED_EXTERNAL),
-		PDO_FIXED(5000,  3000, 0),
-		PDO_FIXED(12000, 3000, 0),
-		PDO_FIXED(20000, 3000, 0),
+		PDO_FIXED(5000,  RATED_CURRENT, 0),
+		PDO_FIXED(12000, RATED_CURRENT, 0),
+		PDO_FIXED(20000, RATED_CURRENT, 0),
 };
 const int pd_src_pdo_cnt = ARRAY_SIZE(pd_src_pdo);
 
diff --git a/chip/stm32/config-stm32f03x.h b/chip/stm32/config-stm32f03x.h
index e7a4a6b3ed..32238c5361 100644
--- a/chip/stm32/config-stm32f03x.h
+++ b/chip/stm32/config-stm32f03x.h
@@ -31,8 +31,7 @@
  * Put pstate after RO to give RW more space and make RO write protect region
  * contiguous.
  */
-#ifdef BOARD_ZINGER
-/* Do not use pstate for zinger. Flash space is limited */
+#if defined(BOARD_ZINGER) || defined(BOARD_MINIMUFFIN)
 #define CONFIG_FW_PSTATE_SIZE   0
 #else
 #define CONFIG_FW_PSTATE_SIZE   CONFIG_FLASH_BANK_SIZE
diff --git a/chip/stm32/usb_pd_phy.c b/chip/stm32/usb_pd_phy.c
index a19bcc7969..041d5b5c58 100644
--- a/chip/stm32/usb_pd_phy.c
+++ b/chip/stm32/usb_pd_phy.c
@@ -456,7 +456,7 @@ void pd_rx_handler(void)
 		}
 	}
 }
-#ifndef BOARD_ZINGER
+#ifdef CONFIG_USB_PD_RX_COMP_IRQ
 DECLARE_IRQ(STM32_IRQ_COMP, pd_rx_handler, 1);
 #endif
 
diff --git a/include/config.h b/include/config.h
index 7902a39639..897478ac18 100644
--- a/include/config.h
+++ b/include/config.h
@@ -1019,6 +1019,9 @@
 /* Define to have PD state machine send read info VDM on connection */
 #undef CONFIG_USB_PD_READ_INFO_ON_CONNECT
 
+/* Use comparator module for PD RX interrupt */
+#define CONFIG_USB_PD_RX_COMP_IRQ
+
 /* USB PD transmit uses SPI master */
 #undef CONFIG_USB_PD_TX_USES_SPI_MASTER
 
diff --git a/util/flash_ec b/util/flash_ec
index 7282381eb9..ec35591481 100755
--- a/util/flash_ec
+++ b/util/flash_ec
@@ -74,6 +74,7 @@ BOARDS_STM32=(
 	spring
 	veyron
 	zinger
+	minimuffin
 )
 
 BOARDS_STM32_PROG_EN=(