auxdisplay: Add driver for MAX695x 7-segment LED controllers

Add initial driver for the MAX6958 and MAX6959 7-segment LED
controllers.

Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/auxdisplay/Kconfig

@@ -177,6 +177,20 @@ config HT16K33
 	  Say yes here to add support for Holtek HT16K33, RAM mapping 16*8
 	  LED controller driver with keyscan.
 
+config MAX6959
+	tristate "Maxim MAX6958/6959 7-segment LED controller"
+	depends on I2C
+	select REGMAP_I2C
+	select LINEDISP
+	help
+	  If you say yes here you get support for the following Maxim chips
+	  (I2C 7-segment LED display controller):
+	  - MAX6958
+	  - MAX6959 (input support)
+
+	  This driver can also be built as a module. If so, the module
+	  will be called max6959.
+
 config LCD2S
 	tristate "lcd2s 20x4 character display over I2C console"
 	depends on I2C

drivers/auxdisplay/Makefile

@@ -14,3 +14,4 @@ obj-$(CONFIG_HT16K33)		+= ht16k33.o
 obj-$(CONFIG_PARPORT_PANEL)	+= panel.o
 obj-$(CONFIG_LCD2S)		+= lcd2s.o
 obj-$(CONFIG_LINEDISP)		+= line-display.o
+obj-$(CONFIG_MAX6959)		+= max6959.o

drivers/auxdisplay/max6959.c

@@ -0,0 +1,194 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * MAX6958/6959 7-segment LED display controller
+ * Datasheet:
+ * https://www.analog.com/media/en/technical-documentation/data-sheets/MAX6958-MAX6959.pdf
+ *
+ * Copyright (c) 2024, Intel Corporation.
+ * Author: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+ */
+#include <linux/array_size.h>
+#include <linux/bitrev.h>
+#include <linux/bits.h>
+#include <linux/container_of.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/pm.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+
+#include <linux/map_to_7segment.h>
+
+#include "line-display.h"
+
+/* Registers */
+#define REG_DECODE_MODE			0x01
+#define REG_INTENSITY			0x02
+#define REG_SCAN_LIMIT			0x03
+#define REG_CONFIGURATION		0x04
+#define REG_CONFIGURATION_S_BIT		BIT(0)
+
+#define REG_DIGIT(x)			(0x20 + (x))
+#define REG_DIGIT0			0x20
+#define REG_DIGIT1			0x21
+#define REG_DIGIT2			0x22
+#define REG_DIGIT3			0x23
+
+#define REG_SEGMENTS			0x24
+#define REG_MAX				REG_SEGMENTS
+
+struct max6959_priv {
+	struct linedisp linedisp;
+	struct delayed_work work;
+	struct regmap *regmap;
+};
+
+static void max6959_disp_update(struct work_struct *work)
+{
+	struct max6959_priv *priv = container_of(work, struct max6959_priv, work.work);
+	struct linedisp *linedisp = &priv->linedisp;
+	struct linedisp_map *map = linedisp->map;
+	char *s = linedisp->buf;
+	u8 buf[4];
+
+	/* Map segments according to datasheet */
+	buf[0] = bitrev8(map_to_seg7(&map->map.seg7, *s++)) >> 1;
+	buf[1] = bitrev8(map_to_seg7(&map->map.seg7, *s++)) >> 1;
+	buf[2] = bitrev8(map_to_seg7(&map->map.seg7, *s++)) >> 1;
+	buf[3] = bitrev8(map_to_seg7(&map->map.seg7, *s++)) >> 1;
+
+	regmap_bulk_write(priv->regmap, REG_DIGIT(0), buf, ARRAY_SIZE(buf));
+}
+
+static int max6959_linedisp_get_map_type(struct linedisp *linedisp)
+{
+	struct max6959_priv *priv = container_of(linedisp, struct max6959_priv, linedisp);
+
+	INIT_DELAYED_WORK(&priv->work, max6959_disp_update);
+	return LINEDISP_MAP_SEG7;
+}
+
+static void max6959_linedisp_update(struct linedisp *linedisp)
+{
+	struct max6959_priv *priv = container_of(linedisp, struct max6959_priv, linedisp);
+
+	schedule_delayed_work(&priv->work, 0);
+}
+
+static const struct linedisp_ops max6959_linedisp_ops = {
+	.get_map_type = max6959_linedisp_get_map_type,
+	.update = max6959_linedisp_update,
+};
+
+static int max6959_enable(struct max6959_priv *priv, bool enable)
+{
+	u8 mask = REG_CONFIGURATION_S_BIT;
+	u8 value = enable ? mask : 0;
+
+	return regmap_update_bits(priv->regmap, REG_CONFIGURATION, mask, value);
+}
+
+static void max6959_power_off(void *priv)
+{
+	max6959_enable(priv, false);
+}
+
+static int max6959_power_on(struct max6959_priv *priv)
+{
+	struct device *dev = regmap_get_device(priv->regmap);
+	int ret;
+
+	ret = max6959_enable(priv, true);
+	if (ret)
+		return ret;
+
+	return devm_add_action_or_reset(dev, max6959_power_off, priv);
+}
+
+static const struct regmap_config max6959_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.max_register = REG_MAX,
+	.cache_type = REGCACHE_MAPLE,
+};
+
+static int max6959_i2c_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct max6959_priv *priv;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->regmap = devm_regmap_init_i2c(client, &max6959_regmap_config);
+	if (IS_ERR(priv->regmap))
+		return PTR_ERR(priv->regmap);
+
+	ret = max6959_power_on(priv);
+	if (ret)
+		return ret;
+
+	ret = linedisp_register(&priv->linedisp, dev, 4, &max6959_linedisp_ops);
+	if (ret)
+		return ret;
+
+	i2c_set_clientdata(client, priv);
+
+	return 0;
+}
+
+static void max6959_i2c_remove(struct i2c_client *client)
+{
+	struct max6959_priv *priv = i2c_get_clientdata(client);
+
+	cancel_delayed_work_sync(&priv->work);
+	linedisp_unregister(&priv->linedisp);
+}
+
+static int max6959_suspend(struct device *dev)
+{
+	return max6959_enable(dev_get_drvdata(dev), false);
+}
+
+static int max6959_resume(struct device *dev)
+{
+	return max6959_enable(dev_get_drvdata(dev), true);
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(max6959_pm_ops, max6959_suspend, max6959_resume);
+
+static const struct i2c_device_id max6959_i2c_id[] = {
+	{ "max6959" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max6959_i2c_id);
+
+static const struct of_device_id max6959_of_table[] = {
+	{ .compatible = "maxim,max6959" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max6959_of_table);
+
+static struct i2c_driver max6959_i2c_driver = {
+	.driver = {
+		.name = "max6959",
+		.pm = pm_sleep_ptr(&max6959_pm_ops),
+		.of_match_table = max6959_of_table,
+	},
+	.probe = max6959_i2c_probe,
+	.remove = max6959_i2c_remove,
+	.id_table = max6959_i2c_id,
+};
+module_i2c_driver(max6959_i2c_driver);
+
+MODULE_DESCRIPTION("MAX6958/6959 7-segment LED controller");
+MODULE_AUTHOR("Andy Shevchenko <andriy.shevchenko@linux.intel.com>");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(LINEDISP);