New patch to review for coreboot: c4bfc5b gpio: Remove non-ternary tristate mode, make ternaries easier

[Patrick Georgi]

Patrick Georgi ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/9401

-gerrit

commit c4bfc5b01c8a1a4f0bd84c7056507827608e0d30
Author: Julius Werner 
Date:   Wed Sep 24 15:40:49 2014 -0700

gpio: Remove non-ternary tristate mode, make ternaries easier

The function to read board IDs from tristate GPIOs currently supports
    two output modes: a normal base-3 integer, or a custom format where
    every two bits represent one tristate pin. Each board decides which
    representation to use on its own, which is inconsistent and provides
    another possible gotcha to trip over when reading unfamiliar code.

The two-bits-per-pin format creates the additional problem that a
    complete list of IDs (such as some boards use to build board-ID tables)
    necessarily has "holes" in them (since 0b11 does not correspond to a
    possible pin state), which makes them extremely tricky to write, read
    and expand. It's also very unintuitive in my opinion, although it was
    intended to make it easier to read individual pin states from a hex
    representation.

This patch switches all boards over to base-3 and removes the other
    format to improve consistency. The tristate reading function will just
    print the pin states as they are read to make it easier to debug them,
    and we add a new BASE3() macro that can generate ternary numbers from
    pin states. Also change the order of all static initializers of board ID
    pin lists to write the most significant bit first, hoping that this can
    help clear up confusion about the endianness of the pins.

CQ-DEPEND=CL:219902
    BUG=None
    TEST=Booted on a Nyan_Blaze (with board ID 1, unfortunately the only one
    I have). Compiled on Daisy, Peach_Pit, Nyan, Nyan_Big, Nyan_Blaze, Rush,
    Rush_Ryu, Storm, Veryon_Pinky and Falco for good measure.

Change-Id: I3ce5a0829f260db7d7df77e6788c2c6d13901b8f
    Signed-off-by: Patrick Georgi 
    Original-Commit-Id: 2fa9545ac431c9af111ee4444d593ee4cf49554d
    Original-Change-Id: I6133cdaf01ed6590ae07e88d9e85a33dc013211a
    Original-Signed-off-by: Julius Werner 
    Original-Reviewed-on: https://chromium-review.googlesource.com/219901
    Original-Reviewed-by: Aaron Durbin 
---
 src/include/base3.h                         | 48 +++++++++++++++++++++++++++++
 src/include/gpio.h                          | 14 +++------
 src/lib/tristate_gpios.c                    | 15 +++++----
 src/mainboard/google/nyan_big/boardid.c     |  8 ++---
 src/mainboard/google/nyan_blaze/boardid.c   |  8 ++---
 src/mainboard/google/rush_ryu/boardid.c     | 46 ++++++++-------------------
 src/mainboard/google/storm/boardid.c        |  4 +--
 src/mainboard/google/veyron_pinky/boardid.c | 10 ++----
 8 files changed, 87 insertions(+), 66 deletions(-)

diff --git a/src/include/base3.h b/src/include/base3.h
new file mode 100644
index 0000000..e92cc8b
--- /dev/null
+++ b/src/include/base3.h
@@ -0,0 +1,48 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2014 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef __SRC_INCLUDE_BASE3_H__
+#define __SRC_INCLUDE_BASE3_H__
+
+/* We translate a floating pin (Z) as the ternary digit 2. */
+#define Z 2
+
+/*
+ * This provides a variadic macro BASE3() that can be used to translate a set of
+ * pin states into its base-3 integer representation, even in the context of a
+ * static initializer. You can call it with any number of up to 6 arguments,
+ * e.g. BASE3(1, Z) -> 5 or BASE3(0, Z, 1, 0) -> 21. Just don't look too closely
+ * at how the sausage is made. (Pay extra attention to typos when expanding it!)
+ */
+#define _BASE3_IMPL_1(arg0, arg1, arg2, arg3, arg4, arg5) arg0
+#define _BASE3_IMPL_2(arg0, arg1, arg2, arg3, arg4, arg5) \
+	(arg1 + (3 * _BASE3_IMPL_1(arg0, arg1, arg2, arg3, arg4, arg5)))
+#define _BASE3_IMPL_3(arg0, arg1, arg2, arg3, arg4, arg5) \
+	(arg2 + (3 * _BASE3_IMPL_2(arg0, arg1, arg2, arg3, arg4, arg5)))
+#define _BASE3_IMPL_4(arg0, arg1, arg2, arg3, arg4, arg5) \
+	(arg3 + (3 * _BASE3_IMPL_3(arg0, arg1, arg2, arg3, arg4, arg5)))
+#define _BASE3_IMPL_5(arg0, arg1, arg2, arg3, arg4, arg5) \
+	(arg4 + (3 * _BASE3_IMPL_4(arg0, arg1, arg2, arg3, arg4, arg5)))
+#define _BASE3_IMPL_6(arg0, arg1, arg2, arg3, arg4, arg5) \
+	(arg5 + (3 * _BASE3_IMPL_5(arg0, arg1, arg2, arg3, arg4, arg5)))
+#define _BASE3_IMPL(arg0, arg1, arg2, arg3, arg4, arg5, NARGS, ...) \
+	_BASE3_IMPL##NARGS(arg0, arg1, arg2, arg3, arg4, arg5)
+#define BASE3(...) _BASE3_IMPL(__VA_ARGS__, _6, _5, _4, _3, _2, _1)
+
+#endif /* __SRC_INCLUDE_BASE3_H__ */
diff --git a/src/include/gpio.h b/src/include/gpio.h
index af06697..b2a341d 100644
--- a/src/include/gpio.h
+++ b/src/include/gpio.h
@@ -36,17 +36,13 @@ void gpio_output(gpio_t gpio, int value);

/*
  * Read the value presented by the set of GPIOs, when each pin is interpreted
- * as a number in 0..2 range depending on the external pullup situation.
+ * as a base-3 digit (LOW = 0, HIGH = 1, Z/floating = 2).
+ * Example: X1 = Z, X2 = 1 -> gpio_get_tristates({GPIO(X1), GPIO(X2)}) = 5
+ * BASE3() from <base3.h> can generate numbers to compare the result to.
  *
- * Depending on the third parameter, the return value is either a set of two
- * bit fields, each representing one GPIO value, or a number where each GPIO is
- * included multiplied by 3^gpio_num, resulting in a true tertiary value.
- *
- * gpio[]: pin positions to read. little-endian (less significant value first).
+ * gpio[]: pin positions to read. gpio[0] is less significant than gpio[1].
  * num_gpio: number of pins to read.
- * tertiary: 1: pins are interpreted as a quad coded tertiary.
- *           0: pins are interpreted as a set of two bit fields.
  */
-int gpio_get_tristates(gpio_t gpio[], int num_gpio, int tertiary);
+int gpio_get_tristates(gpio_t gpio[], int num_gpio);

#endif /* __SRC_INCLUDE_GPIO_H__ */
diff --git a/src/lib/tristate_gpios.c b/src/lib/tristate_gpios.c
index 5ee5580..0967a8f 100644
--- a/src/lib/tristate_gpios.c
+++ b/src/lib/tristate_gpios.c
@@ -17,10 +17,12 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  */

+#include <base3.h>
+#include <console/console.h>
 #include <delay.h>
 #include <gpio.h>

-int gpio_get_tristates(gpio_t gpio[], int num_gpio, int tertiary)
+int gpio_get_tristates(gpio_t gpio[], int num_gpio)
 {
    /*
     * GPIOs which are tied to stronger external pull up or pull down
@@ -31,6 +33,7 @@ int gpio_get_tristates(gpio_t gpio[], int num_gpio, int tertiary)
     * internally pulled to.
     */

+	static const char tristate_char[] = {[0] = '0', [1] = '1', [Z] = 'Z'};
    int temp;
    int index;
    int id = 0;
@@ -62,14 +65,14 @@ int gpio_get_tristates(gpio_t gpio[], int num_gpio, int tertiary)
     *  1: pull up
     *  2: floating
     */
+	printk(BIOS_DEBUG, "Reading tristate GPIOs: ");
    for (index = num_gpio - 1; index >= 0; --index) {
-		if (tertiary)
-			id *= 3;
-		else
-			id <<= 2;
    	temp = gpio_get(gpio[index]);
-		id += ((value[index] ^ temp) << 1) | temp;
+		temp |= ((value[index] ^ temp) << 1);
+		printk(BIOS_DEBUG, "%c ", tristate_char[temp]);
+		id = (id * 3) + temp;
    }
+	printk(BIOS_DEBUG, "= %d\n", id);

/* Disable pull up / pull down to conserve power */
    for (index = 0; index < num_gpio; ++index)
diff --git a/src/mainboard/google/nyan_big/boardid.c b/src/mainboard/google/nyan_big/boardid.c
index 00f646d..b420f5a 100644
--- a/src/mainboard/google/nyan_big/boardid.c
+++ b/src/mainboard/google/nyan_big/boardid.c
@@ -25,13 +25,13 @@
 uint8_t board_id(void)
 {
    static int id = -1;
+	gpio_t gpio[] = {[3] = GPIO(X4), [2] = GPIO(X1),	/* X4 is MSB */
+			 [1] = GPIO(T1), [0] = GPIO(Q3),};	/* Q3 is LSB */

if (id < 0) {
-		gpio_t gpio[] = {GPIO(Q3), GPIO(T1), GPIO(X1), GPIO(X4)};
+		id = gpio_get_tristates(gpio, ARRAY_SIZE(gpio));

-		id = gpio_get_tristates(gpio, ARRAY_SIZE(gpio), 0);
-
-		printk(BIOS_SPEW, "Board TRISTATE ID: %#x.\n", id);
+		printk(BIOS_SPEW, "Board TRISTATE ID: %d.\n", id);
    }

return id;
diff --git a/src/mainboard/google/nyan_blaze/boardid.c b/src/mainboard/google/nyan_blaze/boardid.c
index 00f646d..b420f5a 100644
--- a/src/mainboard/google/nyan_blaze/boardid.c
+++ b/src/mainboard/google/nyan_blaze/boardid.c
@@ -25,13 +25,13 @@
 uint8_t board_id(void)
 {
    static int id = -1;
+	gpio_t gpio[] = {[3] = GPIO(X4), [2] = GPIO(X1),	/* X4 is MSB */
+			 [1] = GPIO(T1), [0] = GPIO(Q3),};	/* Q3 is LSB */

if (id < 0) {
-		gpio_t gpio[] = {GPIO(Q3), GPIO(T1), GPIO(X1), GPIO(X4)};
+		id = gpio_get_tristates(gpio, ARRAY_SIZE(gpio));

-		id = gpio_get_tristates(gpio, ARRAY_SIZE(gpio), 0);
-
-		printk(BIOS_SPEW, "Board TRISTATE ID: %#x.\n", id);
+		printk(BIOS_SPEW, "Board TRISTATE ID: %d.\n", id);
    }

return id;
diff --git a/src/mainboard/google/rush_ryu/boardid.c b/src/mainboard/google/rush_ryu/boardid.c
index ba3a4be..5b4c1cd 100644
--- a/src/mainboard/google/rush_ryu/boardid.c
+++ b/src/mainboard/google/rush_ryu/boardid.c
@@ -17,35 +17,13 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  */

+#include <base3.h>
 #include <boardid.h>
 #include <console/console.h>
 #include <stdlib.h>

#include "gpio.h"

-/*
- * +------------------+---------+
- * | BD_ID_STRAP[1:0] |  PHASE  |
- * +------------------+---------+
- * |         00       |  PROTO0 |
- * +------------------+---------+
- * |         01       |  PROTO1 |
- * +------------------+---------+
- * |         0Z       |   EVT   |
- * +------------------+---------+
- * |         10       |   DVT   |
- * +------------------+---------+
- * |         11       |   PVT   |
- * +------------------+---------+
- * |         1Z       |   MP    |
- * +------------------+---------+
- * |         Z0       |         |
- * +------------------+---------+
- * |         Z1       |         |
- * +------------------+---------+
- * |         ZZ       |         |
- * +------------------+---------+
- */
 struct id_to_str {
    const char *str;
    int tri_state_value;
@@ -53,15 +31,15 @@ struct id_to_str {
 };

static const struct id_to_str bdid_map[] = {
-	{ "PROTO 0", 0x00, BOARD_ID_PROTO_0 },
-	{ "PROTO 1", 0x01, BOARD_ID_PROTO_1 },
-	{ "EVT", 0x02, BOARD_ID_EVT },
-	{ "DVT", 0x04, BOARD_ID_DVT },
-	{ "PVT", 0x05, BOARD_ID_PVT },
-	{ "MP", 0x06, BOARD_ID_MP },
-	{ "Z0", 0x08, -1 },
-	{ "Z1", 0x09, -1 },
-	{ "ZZ", 0x0a, -1 },
+	{ "PROTO 0",	BASE3(0, 0),	BOARD_ID_PROTO_0 },
+	{ "PROTO 1",	BASE3(0, 1),	BOARD_ID_PROTO_1 },
+	{ "EVT",	BASE3(0, Z),	BOARD_ID_EVT },
+	{ "DVT",	BASE3(1, 0),	BOARD_ID_DVT },
+	{ "PVT",	BASE3(1, 1),	BOARD_ID_PVT },
+	{ "MP",		BASE3(1, Z),	BOARD_ID_MP },
+	{ "Z0",		BASE3(Z, 0),	-1 },
+	{ "Z1",		BASE3(Z, 1),	-1 },
+	{ "ZZ",		BASE3(Z, Z),	-1 },
 };

uint8_t board_id(void)
@@ -72,9 +50,9 @@ uint8_t board_id(void)
    	const char *idstr = "Unknown";
    	int i;
    	int tristate_id;
-		gpio_t gpio[] = { BD_ID0, BD_ID1 };
+		gpio_t gpio[] = {[1] = BD_ID1, [0] = BD_ID0};	/* ID0 is LSB */

-		tristate_id = gpio_get_tristates(gpio, ARRAY_SIZE(gpio), 0);
+		tristate_id = gpio_get_tristates(gpio, ARRAY_SIZE(gpio));

for (i = 0; i < ARRAY_SIZE(bdid_map); i++) {
    		if (tristate_id != bdid_map[i].tri_state_value)
diff --git a/src/mainboard/google/storm/boardid.c b/src/mainboard/google/storm/boardid.c
index 878598b..c32567e 100644
--- a/src/mainboard/google/storm/boardid.c
+++ b/src/mainboard/google/storm/boardid.c
@@ -42,10 +42,10 @@ static int board_id_value = -1;
 static uint8_t get_board_id(void)
 {
    uint8_t bid;
-	gpio_t hw_rev_gpios[] = {29, 30, 68};
+	gpio_t hw_rev_gpios[] = {[2] = 68, [1] = 30, [0] = 29};	/* 29 is LSB */
    int offset = 19;

-	bid = gpio_get_tristates(hw_rev_gpios, ARRAY_SIZE(hw_rev_gpios), 1);
+	bid = gpio_get_tristates(hw_rev_gpios, ARRAY_SIZE(hw_rev_gpios));
    bid = (bid + offset) % 27;
    printk(BIOS_INFO, "Board ID %d\n", bid);

diff --git a/src/mainboard/google/veyron_pinky/boardid.c b/src/mainboard/google/veyron_pinky/boardid.c
index d8f4a3d..8d3e183 100644
--- a/src/mainboard/google/veyron_pinky/boardid.c
+++ b/src/mainboard/google/veyron_pinky/boardid.c
@@ -25,12 +25,8 @@
 uint8_t board_id(void)
 {
    static int id = -1;
-	static const gpio_t pins[] = {
-		{ .port = 2, .bank = GPIO_A, .idx = 0 },
-		{ .port = 2, .bank = GPIO_A, .idx = 1 },
-		{ .port = 2, .bank = GPIO_A, .idx = 2 },
-		{ .port = 2, .bank = GPIO_A, .idx = 7 },
-	};
+	static const gpio_t pins[] = {[3] = GPIO(2, A, 7), [2] = GPIO(2, A, 2),
+		[1] = GPIO(2, A, 1), [0] = GPIO(2, A, 0)}; /* GPIO2_A0 is LSB */

if (id < 0) {
    	int i;
@@ -40,7 +36,7 @@ uint8_t board_id(void)
    		gpio_input(pins[i]);
    		id |= gpio_get(pins[i]) << i;
    	}
-		printk(BIOS_SPEW, "Board ID: %#x.\n", id);
+		printk(BIOS_SPEW, "Board ID: %d.\n", id);
    }

return id;