bmips: add support for Sercomm SHG2500

Sercomm SHG2500 is a BCM63168 with 128M of RAM, 256M of NAND, an external
BCM53124S switch for the LAN ports and internal/external Broadcom wifi.
LEDs are connected to an external MSP430G2513 MCU controlled via SPI.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

1 files changed, 380 insertions, 0 deletions

diff --git a/target/linux/bmips/files/drivers/leds/leds-sercomm-msp430.c b/target/linux/bmips/files/drivers/leds/leds-sercomm-msp430.c
new file mode 100644
index 0000000000..5409142989
--- /dev/null
+++ b/target/linux/bmips/files/drivers/leds/leds-sercomm-msp430.c
@@ -0,0 +1,380 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for Sercomm MSP430G2513 LEDs.
+ *
+ * Copyright 2023 Álvaro Fernández Rojas <noltari@gmail.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/spi/spi.h>
+#include "leds.h"
+
+/*
+ * MSP430G2513 SPI protocol description:
+ * +----+----+----+----+----+----+
+ * | b1 | b2 | b3 | b4 | b5 | b6 |
+ * +----+----+----+----+----+----+
+ * 6 bytes TX & RX per transaction.
+ *
+ * LEDs:
+ * MSP430G2513 can control up to 9 LEDs.
+ * b1: LED ID [1,9]
+ * b2: LED function
+ * b3-b6: LED function parameters
+ *
+ * LED functions:
+ * [0] Off
+ * [1] On
+ * [2] Flash
+ *   - b4: delay (x 6ms)
+ *   - b5: repeat (0 = infinite)
+ * [3] Pulse
+ *   - b3: delay (x 6ms)
+ *   - b4: blink while pulsing? (unknown)
+ *   - b5: repeat (0 = infinite)
+ * [4] Pulse On
+ *   - b3: delay (x 6ms)
+ *   - b4: blink while pulsing? (unknown)
+ *   - b5: repeat (0 = infinite)
+ * [5] Pulse Off
+ *   - b3: delay (x 6ms)
+ *   - b4: blink while pulsing? (unknown)
+ *   - b5: repeat (0 = infinite)
+ * [6] Level
+ *   - b3: brightness [0,4]
+ *
+ * MCU Commands (b1 = 0x55):
+ * [0x0a] FW upgrade data
+ *   - b3: Data size (usually 0x40), which is appended to TX & RX.
+ * [0x31] Get MCU version? (unknown)
+ * [0x68] Get MCU work mode
+ * [0xa5] Start FW upgrade
+ * [0xf0] End FW upgrade
+ */
+
+#define MSP430_CMD_BYTES		6
+#define MSP430_CMD_MCU			0x55
+#define MSP430_MCU_WM			0x68
+
+#define MSP430_LED_MIN_ID		1
+#define MSP430_LED_MAX_ID		9
+
+#define MSP430_LED_OFF			0
+#define MSP430_LED_ON			1
+#define MSP430_LED_FLASH		2
+#define MSP430_LED_PULSE		3
+#define MSP430_LED_PULSE_ON		4
+#define MSP430_LED_PULSE_OFF		5
+#define MSP430_LED_LEVEL		6
+
+#define MSP430_LED_BLINK_DEF		500
+#define MSP430_LED_BLINK_MASK		0xff
+#define MSP430_LED_BLINK_MS		6
+#define MSP430_LED_BLINK_MAX		(MSP430_LED_BLINK_MS * \
+					 MSP430_LED_BLINK_MASK)
+
+#define MSP430_LED_BRIGHTNESS_MAX	5
+#define MSP430_LED_REPEAT_MAX		0xff
+
+/**
+ * struct msp430_led - state container for Sercomm MSP430 based LEDs
+ * @cdev: LED class device for this LED
+ * @spi: spi resource
+ * @id: LED ID
+ */
+struct msp430_led {
+	struct led_classdev cdev;
+	struct spi_device *spi;
+	u8 id;
+};
+
+static inline int msp430_cmd(struct spi_device *spi, u8 tx[MSP430_CMD_BYTES],
+			     u8 rx[MSP430_CMD_BYTES])
+{
+	struct device *dev = &spi->dev;
+	int rc;
+
+	memset(rx, 0, MSP430_CMD_BYTES);
+
+	rc = spi_write_then_read(spi, tx, MSP430_CMD_BYTES,
+				  rx, MSP430_CMD_BYTES);
+	if (rc)
+		dev_err(dev, "spi error\n");
+
+	dev_dbg(dev, "msp430_cmd: [%02x %02x %02x %02x %02x %02x]"
+		" -> [%02x %02x %02x %02x %02x %02x]",
+		tx[0], tx[1], tx[2], tx[3], tx[4], tx[5],
+		rx[0], rx[1], rx[2], rx[3], rx[4], rx[5]);
+
+	return rc;
+}
+
+static unsigned long msp430_blink_delay(unsigned long delay)
+{
+	unsigned long msp430_delay;
+
+	msp430_delay = delay + MSP430_LED_BLINK_MS / 2;
+	msp430_delay = msp430_delay / MSP430_LED_BLINK_MS;
+	if (msp430_delay == 0)
+		msp430_delay = 1;
+
+	return msp430_delay;
+}
+
+static int msp430_blink_set(struct led_classdev *led_cdev,
+			    unsigned long *delay_on,
+			    unsigned long *delay_off)
+{
+	struct msp430_led *led =
+		container_of(led_cdev, struct msp430_led, cdev);
+	u8 tx[MSP430_CMD_BYTES] = {led->id, MSP430_LED_FLASH, 0, 0, 0, 0};
+	u8 rx[MSP430_CMD_BYTES];
+	unsigned long delay;
+
+	if (!*delay_on)
+		*delay_on = MSP430_LED_BLINK_DEF;
+	if (!*delay_off)
+		*delay_off = MSP430_LED_BLINK_DEF;
+
+	delay = msp430_blink_delay(*delay_on);
+	if (delay != msp430_blink_delay(*delay_off)) {
+		dev_dbg(led_cdev->dev,
+			"fallback to soft blinking (delay_on != delay_off)\n");
+		return -EINVAL;
+	}
+
+	if (delay > MSP430_LED_BLINK_MASK) {
+		dev_dbg(led_cdev->dev,
+			"fallback to soft blinking (delay > %ums)\n",
+			MSP430_LED_BLINK_MAX);
+		return -EINVAL;
+	}
+
+	tx[3] = delay;
+
+	return msp430_cmd(led->spi, tx, rx);
+}
+
+static int msp430_brightness_set(struct led_classdev *led_cdev,
+				 enum led_brightness brightness)
+{
+	struct msp430_led *led =
+		container_of(led_cdev, struct msp430_led, cdev);
+	u8 tx[MSP430_CMD_BYTES] = {led->id, 0, 0, 0, 0, 0};
+	u8 rx[MSP430_CMD_BYTES];
+	u8 val = (u8) brightness;
+
+	switch (val)
+	{
+	case LED_OFF:
+		tx[1] = MSP430_LED_OFF;
+		break;
+	case MSP430_LED_BRIGHTNESS_MAX:
+		tx[1] = MSP430_LED_ON;
+		break;
+	default:
+		tx[1] = MSP430_LED_LEVEL;
+		tx[2] = val - 1;
+		break;
+	}
+
+	return msp430_cmd(led->spi, tx, rx);
+}
+
+static int msp430_pattern_clear(struct led_classdev *ldev)
+{
+	msp430_brightness_set(ldev, LED_OFF);
+
+	return 0;
+}
+
+static int msp430_pattern_set(struct led_classdev *led_cdev,
+			      struct led_pattern *pattern,
+			      u32 len, int repeat)
+{
+	struct msp430_led *led =
+		container_of(led_cdev, struct msp430_led, cdev);
+	u8 tx[MSP430_CMD_BYTES] = {led->id, 0, 0, 0, 0, 0};
+	u8 rx[MSP430_CMD_BYTES];
+	unsigned long delay0;
+	unsigned long delay1;
+	int rc;
+
+	if (len != 2 ||
+	    repeat > MSP430_LED_REPEAT_MAX ||
+	    pattern[0].delta_t > MSP430_LED_BLINK_MAX ||
+	    pattern[1].delta_t > MSP430_LED_BLINK_MAX)
+		return -EINVAL;
+
+	delay0 = msp430_blink_delay(pattern[0].delta_t);
+	delay1 = msp430_blink_delay(pattern[1].delta_t);
+
+	/* Pulse: <off> <delay> <max> <delay> */
+	if (delay0 == delay1 &&
+	    pattern[0].brightness == LED_OFF &&
+	    pattern[1].brightness == MSP430_LED_BRIGHTNESS_MAX)
+	{
+		tx[1] = MSP430_LED_PULSE;
+		tx[2] = delay0;
+		tx[4] = (u8) repeat;
+	}
+
+	/* Pulse On: <off> <delay> <max> <0ms> */
+	if (pattern[0].delta_t != 0 &&
+	    pattern[1].delta_t == 0 &&
+	    pattern[0].brightness == LED_OFF &&
+	    pattern[1].brightness == MSP430_LED_BRIGHTNESS_MAX) {
+		tx[1] = MSP430_LED_PULSE_ON;
+		tx[2] = delay0;
+		tx[4] = (u8) repeat;
+	}
+
+	/* Pulse Off: <max> <delay> <off> <0ms> */
+	if (pattern[0].delta_t != 0 &&
+	    pattern[1].delta_t == 0 &&
+	    pattern[0].brightness == MSP430_LED_BRIGHTNESS_MAX &&
+	    pattern[1].brightness == LED_OFF) {
+		tx[1] = MSP430_LED_PULSE_OFF;
+		tx[2] = delay0;
+		tx[4] = (u8) repeat;
+	}
+
+	if (!tx[1])
+		return -EINVAL;
+
+	rc = msp430_cmd(led->spi, tx, rx);
+	if (rc)
+		return rc;
+
+	return 0;
+}
+
+static int msp430_led(struct spi_device *spi, struct device_node *nc, u8 id)
+{
+	struct device *dev = &spi->dev;
+	struct led_init_data init_data = {};
+	struct msp430_led *led;
+	enum led_default_state state;
+	int rc;
+
+	led = devm_kzalloc(dev, sizeof(*led), GFP_KERNEL);
+	if (!led)
+		return -ENOMEM;
+
+	led->id = id;
+	led->spi = spi;
+
+	init_data.fwnode = of_fwnode_handle(nc);
+
+	state = led_init_default_state_get(init_data.fwnode);
+	switch (state) {
+	case LEDS_DEFSTATE_ON:
+		led->cdev.brightness = MSP430_LED_BRIGHTNESS_MAX;
+		break;
+	default:
+		led->cdev.brightness = LED_OFF;
+		break;
+	}
+
+	msp430_brightness_set(&led->cdev, led->cdev.brightness);
+
+	led->cdev.blink_set = msp430_blink_set;
+	led->cdev.brightness_set_blocking = msp430_brightness_set;
+	led->cdev.max_brightness = MSP430_LED_BRIGHTNESS_MAX;
+	led->cdev.pattern_clear = msp430_pattern_clear;
+	led->cdev.pattern_set = msp430_pattern_set;
+
+	rc = devm_led_classdev_register_ext(dev, &led->cdev, &init_data);
+	if (rc < 0)
+		return rc;
+
+	dev_dbg(dev, "registered LED %s\n", led->cdev.name);
+
+	return 0;
+}
+
+static inline int msp430_check_workmode(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	u8 tx[MSP430_CMD_BYTES] = {MSP430_CMD_MCU, MSP430_MCU_WM, 0, 0, 0, 0};
+	u8 rx[MSP430_CMD_BYTES];
+	int rc;
+
+	rc = msp430_cmd(spi, tx, rx);
+	if (rc)
+		return rc;
+
+	if ((rx[3] == 0xA5 && rx[4] == 'Z') ||
+	    (rx[4] == 0xA5 && rx[5] == 'Z') ||
+	    (rx[4] == '\b' && rx[5] == '\n')) {
+		dev_err(dev, "invalid workmode: "
+			"[%02x %02x %02x %02x %02x %02x]\n",
+			rx[0], rx[1], rx[2], rx[3], rx[4], rx[5]);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int msp430_leds_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct device_node *np = dev_of_node(dev);
+	struct device_node *child;
+	int rc;
+
+	rc = msp430_check_workmode(spi);
+	if (rc)
+		return rc;
+
+	for_each_available_child_of_node(np, child) {
+		u32 reg;
+
+		if (of_property_read_u32(child, "reg", &reg))
+			continue;
+
+		if (reg < MSP430_LED_MIN_ID || reg > MSP430_LED_MAX_ID) {
+			dev_err(dev, "invalid LED (%u) [%d, %d]\n", reg,
+				MSP430_LED_MIN_ID, MSP430_LED_MAX_ID);
+			continue;
+		}
+
+		rc = msp430_led(spi, child, reg);
+		if (rc < 0) {
+			of_node_put(child);
+			return rc;
+		}
+	}
+
+	return 0;
+}
+
+static const struct of_device_id msp430_leds_of_match[] = {
+	{ .compatible = "sercomm,msp430-leds", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, msp430_leds_of_match);
+
+static const struct spi_device_id msp430_leds_id_table[] = {
+	{ "msp430-leds", 0 },
+	{ }
+};
+
+static struct spi_driver msp430_leds_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = msp430_leds_of_match,
+	},
+	.id_table = msp430_leds_id_table,
+	.probe = msp430_leds_probe,
+};
+
+module_spi_driver(msp430_leds_driver);
+
+MODULE_AUTHOR("Álvaro Fernández Rojas <noltari@gmail.com>");
+MODULE_DESCRIPTION("LED driver for Sercomm MSP430 controllers");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:leds-sercomm-msp430");