driver/max695x: Add 7 segment display driver

Port80 information and power sequencing states can be displayed on the
7-segment so that we can observe its information without connecting a
debugger. Adding this CL to initialize and write to the 7-segment display.

For port80, 80(data) gets displayed on the seven segment, for the
power states, EC(state) gets displayed on the seven segment.

The MAX6958/MAX6959 is a compact multiplexed common - cathode display
designed to interface microprocessors with seven - segment numerical LED
digits or to discrete LEDs via a 2-wire serial interface compatible with
SMBusTM and I2C. The 2-wire serial interface uses fixed logic thresholds
of 0.8V/2.1V when the display driver is powered from a 5V supply for
compatibility with 2.5V and 3.3V systems.

BRANCH=None
BUG=b:130738086
TEST=Manually tested on intelrvp, able to write to the 7 segment display

Change-Id: I82ba3aca40640e094463669aa1ff106ce7b99b7b
Signed-off-by: Ayushee <ayushee.shah@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/1574665
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Ayushee Shah <ayushee.shah@intel.com>
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>

1 files changed, 123 insertions, 0 deletions

diff --git a/driver/led/max695x.c b/driver/led/max695x.c
new file mode 100644
index 0000000000..a563edaf26
--- /dev/null
+++ b/driver/led/max695x.c
@@ -0,0 +1,123 @@
+/* Copyright 2019 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * MAX6958/MAX6959 7-Segment LED Display Driver
+ */
+
+#include "common.h"
+#include "console.h"
+#include "display_7seg.h"
+#include "hooks.h"
+#include "i2c.h"
+#include "max695x.h"
+#include "util.h"
+
+#define CPRINTS(format, args...) cprints(CC_SYSTEM, format, ## args)
+
+static inline int max695x_i2c_write8(uint8_t offset, uint8_t data)
+{
+	return i2c_write8(I2C_PORT_PORT80, PORT80_I2C_ADDR,
+			   offset, (int)data);
+}
+
+static inline int max695x_i2c_write(uint8_t offset, uint8_t *data, int len)
+{
+	/*
+	 * The address pointer stored in the MAX695x increments after
+	 * each data byte is written unless the address equals 01111111
+	 */
+	return i2c_write_block(I2C_PORT_PORT80, PORT80_I2C_ADDR,
+			   offset, data, len);
+}
+
+int display_7seg_write(enum seven_seg_module_display module, uint16_t data)
+{
+	uint8_t buf[4];
+
+	/*
+	 * Convert the data into binary coded hexadecimal value i.e.
+	 * in hexadecimal code-decode mode, the decoder prints 1 byte
+	 * on two segments. It checks the lower nibble of the data in
+	 * the digit register (D3–D0), disregarding bits D7–D4. Hence,
+	 * preparing the hexadecimal buffer to be sent.
+	 *
+	 * Segment 3-2 : Module name
+	 *	  0xEC : EC
+	 *	  0x80 : PORT80
+	 * Segment 1-0 : Data
+	 * For console Command segment 3-0 : Data
+	 */
+	switch (module) {
+	case SEVEN_SEG_CONSOLE_DISPLAY:
+		/* Segment - 3 */
+		buf[0] = (data >> 12) & 0x0F;
+		/* Segment - 2 */
+		buf[1] = (data >> 8) & 0x0F;
+		break;
+	case SEVEN_SEG_EC_DISPLAY:
+		/* Segment - 3 */
+		buf[0] = 0x0E;
+		/* Segment - 2 */
+		buf[1] = 0x0C;
+		break;
+	case SEVEN_SEG_PORT80_DISPLAY:
+		/* Segment - 3 */
+		buf[0] = 0x08;
+		/* Segment - 2 */
+		buf[1] = 0x00;
+		break;
+	default:
+		CPRINTS("Unknown Module\n");
+		return EC_ERROR_UNKNOWN;
+	}
+	/* Segment - 1 */
+	buf[2] = (data >> 4) & 0x0F;
+	/* Segment - 0 */
+	buf[3] = data & 0x0F;
+
+	return max695x_i2c_write(MAX695X_DIGIT0_ADDR, buf, ARRAY_SIZE(buf));
+}
+
+/**
+ * Initialise MAX656x 7-segment display.
+ */
+static void max695x_init(void)
+{
+	uint8_t buf[4] = {
+		[0] = MAX695X_DECODE_MODE_HEX_DECODE,
+		[1] = MAX695X_INTENSITY_MEDIUM,
+		[2] = MAX695X_SCAN_LIMIT_4,
+		[3] = MAX695X_CONFIG_OPR_NORMAL
+	};
+	max695x_i2c_write(MAX695X_REG_DECODE_MODE, buf, ARRAY_SIZE(buf));
+}
+DECLARE_HOOK(HOOK_INIT, max695x_init, HOOK_PRIO_DEFAULT);
+
+static void max695x_shutdown(void)
+{
+	max695x_i2c_write8(MAX695X_REG_CONFIG,
+			   MAX695X_CONFIG_OPR_SHUTDOWN);
+}
+DECLARE_HOOK(HOOK_CHIPSET_SHUTDOWN, max695x_shutdown, HOOK_PRIO_DEFAULT);
+
+#ifdef CONFIG_CMD_SEVEN_SEG_DISPLAY
+static int console_command_max695x_write(int argc, char **argv)
+{
+	char *e;
+	int val;
+
+	if (argc < 2)
+		return EC_ERROR_PARAM_COUNT;
+
+	/* Get value to be written to the seven segment display*/
+	val = strtoi(argv[1], &e, 0);
+	if (*e || val < 0 || val > UINT16_MAX)
+		return EC_ERROR_PARAM1;
+
+	return display_7seg_write(SEVEN_SEG_CONSOLE_DISPLAY, val);
+}
+DECLARE_CONSOLE_COMMAND(seg, console_command_max695x_write,
+			"<val>",
+			"Write to 7 segment display in hex");
+#endif