ec/acpi: Rework to reduce code duplication

- Move EC send/receive polling code to their own functions
- Add named constants for poll timeouts and delay interval
- Use human-readable timeout values
- Add `send`/`recv` functions which support custom timeouts
- Remove extra 10us delays between polling and performing a given
  transaction
- Use constants from `ec.h` for standard EC command opcodes

Tested on a Lenovo Edge E530, which takes similar code paths to
the Lenovo Twist S230u.

Change-Id: Ifda5c030ff81f1046be58aa1fcafdcf71a27cd41
Signed-off-by: Abel Briggs <abelbriggs1@hotmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64012
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Lean Sheng Tan <sheng.tan@9elements.com>

2 files changed, 60 insertions, 51 deletions

diff --git a/src/ec/acpi/ec.c b/src/ec/acpi/ec.c
index 76ec8fe2bdae..7d495a1264fc 100644
--- a/src/ec/acpi/ec.c
+++ b/src/ec/acpi/ec.c
@@ -1,88 +1,92 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
 #include <console/console.h>
-#include <device/device.h>
 #include <arch/io.h>
 #include <delay.h>
-#include <stdint.h>
+#include <types.h>
 #include "ec.h"
 
+#define EC_POLL_DELAY_US	10
+#define EC_SEND_TIMEOUT_US	20000	// 20ms
+#define EC_RECV_TIMEOUT_US	320000	// 320ms
+
 static u16 ec_cmd_reg = EC_SC;
 static u16 ec_data_reg = EC_DATA;
 
+/*
+ * Poll the EC status/command register for a specified
+ * state until the given timeout elapses.
+ */
+static int wait_ec_sc(int timeout_us, u8 mask, u8 state)
+{
+	while (timeout_us > 0 && (inb(ec_cmd_reg) & mask) != state) {
+		udelay(EC_POLL_DELAY_US);
+		timeout_us -= EC_POLL_DELAY_US;
+	}
+
+	return timeout_us > 0 ? 0 : -1;
+}
+
+bool ec_ready_send(int timeout_us)
+{
+	return wait_ec_sc(timeout_us, EC_IBF, 0) == 0;
+}
+
+bool ec_ready_recv(int timeout_us)
+{
+	return wait_ec_sc(timeout_us, EC_OBF, EC_OBF) == 0;
+}
+
 int send_ec_command(u8 command)
 {
-	int timeout;
+	return send_ec_command_timeout(command, EC_SEND_TIMEOUT_US);
+}
 
-	timeout = 0x7ff;
-	while ((inb(ec_cmd_reg) & EC_IBF) && --timeout) {
-		udelay(10);
-		if ((timeout & 0xff) == 0)
-			printk(BIOS_SPEW, ".");
-	}
-	if (!timeout) {
+int send_ec_command_timeout(u8 command, int timeout_us)
+{
+	if (!ec_ready_send(timeout_us)) {
 		printk(BIOS_DEBUG, "Timeout while sending command 0x%02x to EC!\n",
 				command);
 		// return -1;
 	}
 
-	udelay(10);
-
 	outb(command, ec_cmd_reg);
+
 	return 0;
 }
 
 int send_ec_data(u8 data)
 {
-	int timeout;
+	return send_ec_data_timeout(data, EC_SEND_TIMEOUT_US);
+}
 
-	timeout = 0x7ff;
-	while ((inb(ec_cmd_reg) & EC_IBF) && --timeout) { // wait for IBF = 0
-		udelay(10);
-		if ((timeout & 0xff) == 0)
-			printk(BIOS_SPEW, ".");
-	}
-	if (!timeout) {
+int send_ec_data_timeout(u8 data, int timeout_us)
+{
+	if (!ec_ready_send(timeout_us)) {
 		printk(BIOS_DEBUG, "Timeout while sending data 0x%02x to EC!\n",
 				data);
 		// return -1;
 	}
 
-	udelay(10);
-
 	outb(data, ec_data_reg);
 
 	return 0;
 }
 
-int send_ec_data_nowait(u8 data)
+u8 recv_ec_data(void)
 {
-	outb(data, ec_data_reg);
-
-	return 0;
+	return recv_ec_data_timeout(EC_RECV_TIMEOUT_US);
 }
 
-u8 recv_ec_data(void)
+u8 recv_ec_data_timeout(int timeout_us)
 {
-	int timeout;
 	u8 data;
 
-	timeout = 0x7fff;
-	while (--timeout) { // Wait for OBF = 1
-		if (inb(ec_cmd_reg) & EC_OBF) {
-			break;
-		}
-		udelay(10);
-		if ((timeout & 0xff) == 0)
-			printk(BIOS_SPEW, ".");
-	}
-	if (!timeout) {
-		printk(BIOS_DEBUG, "\nTimeout while receiving data from EC!\n");
+	if (!ec_ready_recv(timeout_us)) {
+		printk(BIOS_DEBUG, "Timeout while receiving data from EC!\n");
 		// return -1;
 	}
 
-	udelay(10);
-
 	data = inb(ec_data_reg);
 	printk(BIOS_SPEW, "%s: 0x%02x\n", __func__, data);
 
@@ -91,14 +95,15 @@ u8 recv_ec_data(void)
 
 void ec_clear_out_queue(void)
 {
-	int timeout = 0x7fff;
+	int timeout = EC_RECV_TIMEOUT_US;
 	printk(BIOS_SPEW, "Clearing EC output queue...\n");
-	while (--timeout && (inb(ec_cmd_reg) & EC_OBF)) {
+	while (timeout > 0 && inb(ec_cmd_reg) & EC_OBF) {
 		u8 data = inb(ec_data_reg);
 		printk(BIOS_SPEW, "Discarding a garbage byte: 0x%02x\n", data);
-		udelay(10);
+		udelay(EC_POLL_DELAY_US);
+		timeout -= EC_POLL_DELAY_US;
 	}
-	if (!timeout)
+	if (timeout <= 0)
 		printk(BIOS_ERR, "Timeout while clearing EC output queue!\n");
 	else
 		printk(BIOS_SPEW, "EC output queue has been cleared.\n");
@@ -106,7 +111,7 @@ void ec_clear_out_queue(void)
 
 u8 ec_read(u8 addr)
 {
-	send_ec_command(0x80);
+	send_ec_command(RD_EC);
 	send_ec_data(addr);
 
 	return recv_ec_data();
@@ -114,7 +119,7 @@ u8 ec_read(u8 addr)
 
 int ec_write(u8 addr, u8 data)
 {
-	send_ec_command(0x81);
+	send_ec_command(WR_EC);
 	send_ec_data(addr);
 	return send_ec_data(data);
 }
@@ -126,7 +131,7 @@ u8 ec_status(void)
 
 u8 ec_query(void)
 {
-	send_ec_command(0x84);
+	send_ec_command(QR_EC);
 	return recv_ec_data();
 }
 
diff --git a/src/ec/acpi/ec.h b/src/ec/acpi/ec.h
index f176d7be03fb..665c62f55908 100644
--- a/src/ec/acpi/ec.h
+++ b/src/ec/acpi/ec.h
@@ -3,7 +3,7 @@
 #ifndef _EC_ACPI_H
 #define _EC_ACPI_H
 
-#include <stdint.h>
+#include <types.h>
 
 #define EC_DATA	0x62
 #define EC_SC	0x66
@@ -11,7 +11,7 @@
 /* EC_SC input */
 #define   EC_SMI_EVT	(1 << 6) // 1: SMI event pending
 #define   EC_SCI_EVT	(1 << 5) // 1: SCI event pending
-#define   EC_BURST	(1 << 4) // controller is in burst mode
+#define   EC_BURST	(1 << 4) // 1: controller is in burst mode
 #define   EC_CMD	(1 << 3) // 1: byte in data register is command
 				 // 0: byte in data register is data
 #define   EC_IBF	(1 << 1) // 1: input buffer full (data ready for ec)
@@ -23,10 +23,14 @@
 #define   BD_EC		0x83 // Burst Disable Embedded Controller
 #define   QR_EC		0x84 // Query Embedded Controller
 
+bool ec_ready_send(int timeout_us);
+bool ec_ready_recv(int timeout_us);
 int send_ec_command(u8 command);
+int send_ec_command_timeout(u8 command, int timeout);
 int send_ec_data(u8 data);
-int send_ec_data_nowait(u8 data);
+int send_ec_data_timeout(u8 data, int timeout);
 u8 recv_ec_data(void);
+u8 recv_ec_data_timeout(int timeout);
 void ec_clear_out_queue(void);
 u8 ec_status(void);
 u8 ec_query(void);