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|
From: Profpatsch <mail@profpatsch.de>
Subject: [PATCH] backlight: Netronix LM3630A frontlight with ntxfw calibration
The tolino vision 6's frontlight is an LM3630A with a warm (bank A) and
a cold (bank B) LED string. Its vendor kernel does not expose the chip's
banks to userspace, but a brightness of 0..100 percent
(/sys/class/backlight/mxc_msp430.0) and a colour temperature
(/sys/class/backlight/lm3630a_led/color), mapped onto both banks'
brightness and current through a calibration table that the bootloader
keeps per device in its "ntxfw" area. KOReader's Kobo backend drives
exactly that interface.
ntx_lm3630a_bl.c does the same: it copies the table out of the ntxfw
area (a reserved-memory region, "memory-region"), registers both
backlight devices under the vendor's names, and programs the chip as the
vendor's lm3630a_bl.c does on this board (chip init on power up, the
enable GPIO off when both banks are off). Mainline's lm3630a_bl, which
exposes the banks with fixed full-scale current, stays as it is.
---
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -384,6 +384,16 @@
help
This supports TI LM3509 Backlight Driver
+config BACKLIGHT_NTX_LM3630A
+ tristate "Netronix frontlight on an LM3630A (ntxfw calibration)"
+ depends on I2C && OF
+ select REGMAP_I2C
+ help
+ The frontlight of Netronix e-readers (tolino vision 6) as their
+ vendor kernel drives it: a percentage and a colour temperature,
+ mapped onto the LM3630A's banks through the calibration table in
+ the bootloader's ntxfw area.
+
config BACKLIGHT_LM3630A
tristate "Backlight Driver for LM3630A"
depends on I2C && PWM
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -40,6 +40,7 @@
obj-$(CONFIG_BACKLIGHT_LM3509) += lm3509_bl.o
obj-$(CONFIG_BACKLIGHT_LM3533) += lm3533_bl.o
obj-$(CONFIG_BACKLIGHT_LM3630A) += lm3630a_bl.o
+obj-$(CONFIG_BACKLIGHT_NTX_LM3630A) += ntx_lm3630a_bl.o
obj-$(CONFIG_BACKLIGHT_LM3639) += lm3639_bl.o
obj-$(CONFIG_BACKLIGHT_LOCOMO) += locomolcd.o
obj-$(CONFIG_BACKLIGHT_LP855X) += lp855x_bl.o
--- /dev/null
+++ b/drivers/video/backlight/ntx_lm3630a_bl.c
@@ -0,0 +1,359 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Netronix frontlight on a TI LM3630A, as the vendor kernel of the tolino
+ * vision 6 drives it (drivers/video/backlight/ntx_bl.c and lm3630a_bl.c
+ * there): one brightness from 0 to 100 percent and a colour temperature,
+ * mapped onto the chip's two banks through the calibration table the
+ * bootloader keeps in its "ntxfw" area (ntxfw_p= on the vendor's command
+ * line), per device.
+ *
+ * Bank A is the warm LED string, bank B the cold one. For each colour
+ * temperature and percentage the table gives both banks' brightness and
+ * current; a current of 0 means the colour's default, and that 0 means the
+ * table header's (on the tolino: A 3, B 2).
+ *
+ * The sysfs interface is the vendor's, which KOReader's Kobo backend uses:
+ * /sys/class/backlight/mxc_msp430.0/brightness 0..100 percent
+ * /sys/class/backlight/lm3630a_led/color 0..max_color
+ * /sys/class/backlight/lm3630a_led/brightness 0..100, the same
+ */
+
+#include <linux/backlight.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/regmap.h>
+#include <linux/unaligned.h>
+
+#define REG_CTRL 0x00
+#define REG_CONFIG 0x01
+#define REG_BOOST 0x02
+#define REG_BRT_A 0x03
+#define REG_BRT_B 0x04
+#define REG_I_A 0x05
+#define REG_I_B 0x06
+#define REG_ONOFF_RAMP 0x07
+#define REG_RUN_RAMP 0x08
+#define REG_REV 0x1f
+#define REG_FILTER_STRENGTH 0x50
+
+#define CTRL_SLEEP BIT(7)
+#define CTRL_LEDA_EN BIT(2)
+#define CTRL_LEDB_EN BIT(1)
+
+/* The bootloader's ntxfw blob (the vendor's ntx_firmware.h). */
+#define NTXFW_SIG_S "{NTXFW-->"
+#define NTXFW_HDR_SIZE 52 /* signature, name, item count, version */
+#define NTXFW_ITEM_HDR_SIZE 56 /* magic, 0x12345678, type, size, name */
+#define NTXFW_TYPE_DUALFL_HDR 6
+#define NTXFW_TYPE_DUALFL_TAB 7
+
+struct ntx_fl_colour { /* NTX_FW_LM3630FL_dualcolor_percent_tab */
+ char name[32];
+ u8 def_cur_a, def_cur_b, def_freq, def_flags;
+ u8 brt_a[100], cur_a[100], brt_b[100], cur_b[100];
+ __le32 total_current[100];
+ u8 reserved[8];
+} __packed;
+
+struct ntx_fl {
+ struct i2c_client *client;
+ struct regmap *regmap;
+ struct gpio_desc *enable;
+ struct mutex lock;
+ struct backlight_device *bl, *bl_led;
+ const struct ntx_fl_colour *colours; /* copied out of ntxfw */
+ unsigned int ncolours;
+ u8 hdr_cur_a, hdr_cur_b;
+ unsigned int percent, colour;
+ bool powered;
+};
+
+static int ntx_fl_chip_init(struct ntx_fl *fl)
+{
+ /* As the vendor's lm3630a_chip_init() on this board. */
+ usleep_range(1000, 2000);
+ return regmap_write(fl->regmap, REG_FILTER_STRENGTH, 0x03) ?:
+ regmap_update_bits(fl->regmap, REG_CONFIG, 0x07, 0x00) ?:
+ regmap_write(fl->regmap, REG_ONOFF_RAMP, 0x00) ?:
+ regmap_write(fl->regmap, REG_RUN_RAMP, 0x00) ?:
+ regmap_write(fl->regmap, REG_BOOST, 0x63) ?:
+ regmap_update_bits(fl->regmap, REG_I_A, 0x1f, 0) ?:
+ regmap_write(fl->regmap, REG_I_B, 0) ?:
+ regmap_update_bits(fl->regmap, REG_CTRL, 0x14, CTRL_LEDA_EN) ?:
+ regmap_update_bits(fl->regmap, REG_CTRL, 0x0b, CTRL_LEDB_EN) ?:
+ regmap_write(fl->regmap, REG_BRT_A, 0) ?:
+ regmap_write(fl->regmap, REG_BRT_B, 0);
+}
+
+/* The vendor's _lm3630a_set_FL(). */
+static int ntx_fl_set(struct ntx_fl *fl, u8 cur_a, u8 brt_a, u8 cur_b, u8 brt_b)
+{
+ unsigned int en = 0;
+ int ret;
+
+ if (!cur_a && !cur_b) {
+ if (fl->powered) {
+ gpiod_set_value_cansleep(fl->enable, 0);
+ fl->powered = false;
+ }
+ return 0;
+ }
+ if (!fl->powered) {
+ gpiod_set_value_cansleep(fl->enable, 1);
+ fl->powered = true;
+ msleep(50);
+ ret = ntx_fl_chip_init(fl);
+ if (ret)
+ return ret;
+ }
+
+ ret = regmap_update_bits(fl->regmap, REG_CTRL, CTRL_SLEEP, 0);
+ if (ret)
+ return ret;
+ usleep_range(1000, 2000);
+
+ ret = regmap_write(fl->regmap, REG_BRT_A, brt_a) ?:
+ regmap_update_bits(fl->regmap, REG_I_A, 0x1f, cur_a & 0x1f) ?:
+ regmap_write(fl->regmap, REG_BRT_B, brt_b) ?:
+ regmap_write(fl->regmap, REG_I_B, cur_b & 0x1f);
+ if (ret)
+ return ret;
+
+ if (cur_a)
+ en |= CTRL_LEDA_EN;
+ if (cur_b)
+ en |= CTRL_LEDB_EN;
+ return regmap_update_bits(fl->regmap, REG_CTRL,
+ CTRL_LEDA_EN | CTRL_LEDB_EN, en);
+}
+
+/* The vendor's _fl_lm3630a_percentage(). */
+static int ntx_fl_apply(struct ntx_fl *fl)
+{
+ const struct ntx_fl_colour *c;
+ unsigned int i;
+ u8 cur_a, cur_b;
+
+ if (!fl->percent)
+ return ntx_fl_set(fl, 0, 0, 0, 0);
+
+ c = &fl->colours[fl->colour];
+ i = fl->percent - 1;
+ cur_a = c->cur_a[i] ?: c->def_cur_a ?: fl->hdr_cur_a ?: 4;
+ cur_b = c->cur_b[i] ?: c->def_cur_b ?: fl->hdr_cur_b ?: 7;
+ return ntx_fl_set(fl, cur_a, c->brt_a[i], cur_b, c->brt_b[i]);
+}
+
+static int ntx_fl_update_status(struct backlight_device *bl)
+{
+ struct ntx_fl *fl = bl_get_data(bl);
+ int ret;
+
+ mutex_lock(&fl->lock);
+ fl->percent = backlight_get_brightness(bl);
+ /* Both devices show the same percentage, as the vendor's do. */
+ if (fl->bl)
+ fl->bl->props.brightness = fl->percent;
+ if (fl->bl_led)
+ fl->bl_led->props.brightness = fl->percent;
+ ret = ntx_fl_apply(fl);
+ mutex_unlock(&fl->lock);
+ return ret;
+}
+
+static const struct backlight_ops ntx_fl_ops = {
+ .options = BL_CORE_SUSPENDRESUME,
+ .update_status = ntx_fl_update_status,
+};
+
+static ssize_t color_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct ntx_fl *fl = bl_get_data(to_backlight_device(dev));
+
+ return sysfs_emit(buf, "%u", fl->colour);
+}
+
+static ssize_t color_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct ntx_fl *fl = bl_get_data(to_backlight_device(dev));
+ unsigned int v;
+ int ret;
+
+ ret = kstrtouint(buf, 10, &v);
+ if (ret)
+ return ret;
+ if (v >= fl->ncolours)
+ return -EINVAL;
+ mutex_lock(&fl->lock);
+ fl->colour = v;
+ ret = ntx_fl_apply(fl);
+ mutex_unlock(&fl->lock);
+ return ret ?: count;
+}
+static DEVICE_ATTR_RW(color);
+
+static ssize_t max_color_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct ntx_fl *fl = bl_get_data(to_backlight_device(dev));
+
+ return sysfs_emit(buf, "%u", fl->ncolours - 1);
+}
+static DEVICE_ATTR_RO(max_color);
+
+static struct attribute *ntx_fl_attrs[] = {
+ &dev_attr_color.attr,
+ &dev_attr_max_color.attr,
+ NULL
+};
+static const struct attribute_group ntx_fl_group = { .attrs = ntx_fl_attrs };
+
+static void ntx_fl_remove_group(void *data)
+{
+ struct backlight_device *bl = data;
+
+ sysfs_remove_group(&bl->dev.kobj, &ntx_fl_group);
+}
+
+/* Find the dual-colour tables in the bootloader's ntxfw area. */
+static int ntx_fl_parse_ntxfw(struct ntx_fl *fl)
+{
+ struct device *dev = &fl->client->dev;
+ struct device_node *np;
+ struct resource res;
+ const u8 *fw, *p, *end;
+ unsigned int items, i;
+ void *map;
+ int ret = -ENOENT;
+
+ np = of_parse_phandle(dev->of_node, "memory-region", 0);
+ if (!np)
+ return dev_err_probe(dev, -EINVAL, "no memory-region (ntxfw)\n");
+ ret = of_address_to_resource(np, 0, &res);
+ of_node_put(np);
+ if (ret)
+ return ret;
+ map = memremap(res.start, resource_size(&res), MEMREMAP_WB);
+ if (!map)
+ return -ENOMEM;
+ fw = map;
+ end = fw + resource_size(&res);
+
+ if (memcmp(fw, NTXFW_SIG_S, sizeof(NTXFW_SIG_S) - 1)) {
+ ret = dev_err_probe(dev, -EINVAL, "no ntxfw at %pR\n", &res);
+ goto out;
+ }
+ items = get_unaligned_le16(fw + 46);
+ p = fw + NTXFW_HDR_SIZE;
+ ret = -ENOENT;
+ for (i = 0; i < items && p + NTXFW_ITEM_HDR_SIZE <= end; i++) {
+ u16 type = get_unaligned_le16(p + 12);
+ u32 size = get_unaligned_le32(p + 16);
+ const u8 *body = p + NTXFW_ITEM_HDR_SIZE;
+
+ if (get_unaligned_le32(p + 8) != 0x12345678 || body + size > end)
+ break;
+ if (type == NTXFW_TYPE_DUALFL_HDR && size >= 6) {
+ fl->ncolours = get_unaligned_le32(body);
+ fl->hdr_cur_a = body[4];
+ fl->hdr_cur_b = body[5];
+ } else if (type == NTXFW_TYPE_DUALFL_TAB && fl->ncolours &&
+ size >= fl->ncolours * sizeof(struct ntx_fl_colour)) {
+ fl->colours = devm_kmemdup(dev, body,
+ fl->ncolours * sizeof(struct ntx_fl_colour),
+ GFP_KERNEL);
+ ret = fl->colours ? 0 : -ENOMEM;
+ }
+ p = body + size;
+ }
+ if (ret == -ENOENT)
+ dev_err(dev, "no LM3630A dual-colour table in ntxfw\n");
+ else if (!ret)
+ dev_info(dev, "%u colour temperatures (default currents %u/%u)\n",
+ fl->ncolours, fl->hdr_cur_a, fl->hdr_cur_b);
+out:
+ memunmap(map);
+ return ret;
+}
+
+static const struct regmap_config ntx_fl_regmap = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ .max_register = REG_FILTER_STRENGTH,
+};
+
+static int ntx_fl_probe(struct i2c_client *client)
+{
+ struct backlight_properties props = {
+ .type = BACKLIGHT_RAW,
+ .max_brightness = 100,
+ };
+ struct device *dev = &client->dev;
+ struct ntx_fl *fl;
+ unsigned int rev;
+ int ret;
+
+ fl = devm_kzalloc(dev, sizeof(*fl), GFP_KERNEL);
+ if (!fl)
+ return -ENOMEM;
+ fl->client = client;
+ mutex_init(&fl->lock);
+
+ ret = ntx_fl_parse_ntxfw(fl);
+ if (ret)
+ return ret;
+
+ fl->regmap = devm_regmap_init_i2c(client, &ntx_fl_regmap);
+ if (IS_ERR(fl->regmap))
+ return PTR_ERR(fl->regmap);
+
+ /* Off at probe; the chip must be enabled to answer, so look. */
+ fl->enable = devm_gpiod_get(dev, "enable", GPIOD_OUT_HIGH);
+ if (IS_ERR(fl->enable))
+ return PTR_ERR(fl->enable);
+ msleep(50);
+ ret = regmap_read(fl->regmap, REG_REV, &rev);
+ if (ret)
+ return dev_err_probe(dev, ret, "no LM3630A\n");
+ gpiod_set_value_cansleep(fl->enable, 0);
+ dev_info(dev, "LM3630A rev 0x%02x\n", rev);
+
+ fl->bl = devm_backlight_device_register(dev, "mxc_msp430.0", dev, fl,
+ &ntx_fl_ops, &props);
+ if (IS_ERR(fl->bl))
+ return PTR_ERR(fl->bl);
+ fl->bl_led = devm_backlight_device_register(dev, "lm3630a_led", dev, fl,
+ &ntx_fl_ops, &props);
+ if (IS_ERR(fl->bl_led))
+ return PTR_ERR(fl->bl_led);
+ ret = sysfs_create_group(&fl->bl_led->dev.kobj, &ntx_fl_group);
+ if (ret)
+ return ret;
+ return devm_add_action_or_reset(dev, ntx_fl_remove_group, fl->bl_led);
+}
+
+static const struct of_device_id ntx_fl_of_match[] = {
+ { .compatible = "netronix,lm3630a-frontlight" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, ntx_fl_of_match);
+
+static struct i2c_driver ntx_fl_driver = {
+ .driver = {
+ .name = "ntx-lm3630a",
+ .of_match_table = ntx_fl_of_match,
+ },
+ .probe = ntx_fl_probe,
+};
+module_i2c_driver(ntx_fl_driver);
+
+MODULE_DESCRIPTION("Netronix LM3630A frontlight with ntxfw calibration");
+MODULE_LICENSE("GPL");
|