Hi Pantelis,

Thanks for the patch. Please find my comments in the code below.

On 10/07/2016 05:21 PM, Pantelis Antoniou wrote:
From: Georgi Vlaev <gvl...@juniper.net>

Add support for the FRU faceplate status LEDs (OK, FAIL,
ACTIVE, STANDBY) controlled by the Juniper I2CS FPGA. This
driver is a jnx-i2cs-core client.

Signed-off-by: Georgi Vlaev <gvl...@juniper.net>
[Ported from Juniper kernel]
Signed-off-by: Pantelis Antoniou <pantelis.anton...@konsulko.com>
---
 drivers/leds/Kconfig         |   9 ++
 drivers/leds/Makefile        |   1 +
 drivers/leds/leds-jnx-i2cs.c | 219 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 229 insertions(+)
 create mode 100644 drivers/leds/leds-jnx-i2cs.c

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 7a628c6..45c6612 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -659,6 +659,15 @@ config LEDS_MLXCPLD
          This option enabled support for the LEDs on the Mellanox
          boards. Say Y to enabled these.

+config LEDS_JNX_I2CS
+       tristate "LED support for the Juniper Networks I2CS FPGA"
+       depends on LEDS_CLASS && I2C
+       select REGMAP_I2C
+       help
+         This option enables support for the FRU faceplate status
+         LEDs (OK, FAIL, ACTIVE, STANDBY) controlled by the Juniper
+         I2CS FPGA.
+
 comment "LED Triggers"
 source "drivers/leds/trigger/Kconfig"

diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index 3965070..1ce2d0b 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -71,6 +71,7 @@ obj-$(CONFIG_LEDS_IS31FL319X)         += leds-is31fl319x.o
 obj-$(CONFIG_LEDS_IS31FL32XX)          += leds-is31fl32xx.o
 obj-$(CONFIG_LEDS_PM8058)              += leds-pm8058.o
 obj-$(CONFIG_LEDS_MLXCPLD)             += leds-mlxcpld.o
+obj-$(CONFIG_LEDS_JNX_I2CS)            += leds-jnx-i2cs.o

 # LED SPI Drivers
 obj-$(CONFIG_LEDS_DAC124S085)          += leds-dac124s085.o
diff --git a/drivers/leds/leds-jnx-i2cs.c b/drivers/leds/leds-jnx-i2cs.c
new file mode 100644
index 0000000..c2d7274
--- /dev/null
+++ b/drivers/leds/leds-jnx-i2cs.c
@@ -0,0 +1,219 @@
+/*
+ * Juniper Networks I2CS FPGA LEDs driver
+ *
+ * Copyright (C) 2016 Juniper Networks
+ * Author: Georgi Vlaev <gvl...@juniper.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/of.h>
+#include <linux/delay.h>
+#include <linux/leds.h>
+#include <linux/i2c.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/jnx-i2cs-core.h>

Please arrange include directives in alphabetical order.

+#define FRU_LEDS       4 /* Total LEDs (active, fail, ok, standby) */
+#define HW_BLINK_LEDS  3 /* LEDs with hw blink cap (standby not supported) */
+
+/*
+ * I2CS fru_led [0x12]
+ *
+ * bit 6   | bit 5    | bit 4   |...                        | bit 0
+ * blink_ok|blink_fail|blink_act|led_standby|led_ok|led_fail|led_act
+ */
+
+/* TODO: Use the regmap from the parent MFD */

Isn't it a good moment to address that?

+static struct regmap_config i2cs_leds_regmap_config = {
+       .reg_bits = 8,
+       .val_bits = 8,
+       .max_register = I2CS_SPARE_OE,
+};
+
+struct i2cs_led {
+       struct led_classdev lc;

Most drivers use led_cdev or cdev name for it.
It is more informative and improves readability.

+       struct regmap *regmap;
+       struct work_struct work;
+       int blink;
+       int on;
+       int bit;
+};
+
+struct i2cs_led_data {
+       int num_leds;
+       struct i2cs_led *leds;
+};
+
+static void jnx_i2cs_leds_work(struct work_struct *work)
+{
+       struct i2cs_led *led = container_of(work, struct i2cs_led, work);
+
+       int mask = (BIT(led->bit) << 4) | BIT(led->bit);
+       int value = ((led->blink << led->bit) << 4) | (led->on << led->bit);
+
+       regmap_update_bits(led->regmap, I2CS_FRU_LED, mask, value & 0x7f);
+}

If you used brightness_set_blocking op instead of brightness_set,
then you could get rid of the in-driver work queue.

+
+static void jnx_i2cs_leds_brightness_set(struct led_classdev *lc,
+                                enum led_brightness brightness)
+{
+       struct i2cs_led *led = container_of(lc, struct i2cs_led, lc);
+
+       led->on = (brightness != LED_OFF);
+       led->blink = 0; /* always turn off hw blink on brightness_set() */

Some time ago we changed brightness setting semantics when blinking
is on. Now setting any brightness > 0 shouldn't disable blinking.
Following commit provides the details:

7cfe749fad51 ("leds: core: Fix brightness setting upon hardware blinking enabled")

It seems that the hardware supports only one brightness level.
In such a case I'd return immediately if the LED is on and
brightness to be set is 1.

+       schedule_work(&led->work);
+}
+
+static int jnx_i2cs_leds_blink_set(struct led_classdev *lc,
+                                  unsigned long *delay_on,
+                                  unsigned long *delay_off)
+{
+       struct i2cs_led *led = container_of(lc, struct i2cs_led, lc);
+
+       led->blink = (*delay_on > 0);

blink_set op should fail if hardware doesn't support delay_on
or delay_off periods. I lets the LED core to apply software blink
fallback.

+       led->on = led->blink; /* 'on' bit should be set if blinking */
+       schedule_work(&led->work);
+
+       return 0;
+}
+
+static int jnx_i2cs_leds_init_one(struct device *dev, struct device_node *np,
+                                 struct i2cs_led_data *ild,
+                                 struct regmap *regmap, int num)
+{
+       struct i2cs_led *led;
+       const char *string;
+       bool hw_blink;
+       int ret;
+       u32 reg;
+
+       ret = of_property_read_u32(np, "reg", &reg);
+       if (ret || reg >= FRU_LEDS)
+               return -ENODEV;
+
+       led = &ild->leds[num];
+       led->bit = reg;
+       led->regmap = regmap;
+
+       if (!of_property_read_string(np, "label", &string))
+               led->lc.name = string;
+       else
+               led->lc.name = np->name;
+
+       if (!of_property_read_string(np, "linux,default-trigger", &string))
+               led->lc.default_trigger = string;
+
+       led->lc.brightness = LED_OFF;
+       led->lc.brightness_set = jnx_i2cs_leds_brightness_set;

You need also:

led->lc.max_brightness = 1;

+       if (led->bit <= HW_BLINK_LEDS) {
+               hw_blink = of_property_read_bool(np, "hw-blink");
+               if (hw_blink)
+                       led->lc.blink_set = jnx_i2cs_leds_blink_set;
+       }
+
+       ret = devm_led_classdev_register(dev, &led->lc);
+       if (ret)
+               return ret;
+
+       INIT_WORK(&led->work, jnx_i2cs_leds_work);
+
+       return 0;
+}
+
+static int jnx_i2cs_leds_of_init(struct device *dev, struct i2cs_led_data *ild)
+{
+       struct device_node *child, *np = dev->of_node;
+       struct regmap *regmap;
+       struct i2c_client *client;
+       int ret, num_leds, i = 0;
+
+       if (!dev->parent)
+               return -ENODEV;
+
+       client = i2c_verify_client(dev->parent);
+       if (!client)
+               return -ENODEV;
+
+       regmap = devm_regmap_init_i2c(client, &i2cs_leds_regmap_config);
+       if (IS_ERR(regmap)) {
+               dev_err(dev, "Failed to allocate register map\n");
+               return PTR_ERR(regmap);
+       }
+
+       num_leds = of_get_child_count(np);
+       if (!num_leds || num_leds > FRU_LEDS)
+               return -ENODEV;
+
+       ild->num_leds = num_leds;
+       ild->leds = devm_kzalloc(dev, sizeof(struct i2cs_led) * num_leds,
+                                GFP_KERNEL);
+       if (!ild->leds)
+               return -ENOMEM;
+
+       for_each_child_of_node(np, child) {
+               ret = jnx_i2cs_leds_init_one(dev, child, ild, regmap, i++);
+               if (ret)
+                       return ret;

of_node_put(child) should be called on error to avoid memory leak.

+       }
+
+       return 0;
+}
+
+static int jnx_i2cs_leds_probe(struct platform_device *pdev)
+{
+       struct device *dev = &pdev->dev;
+       struct i2cs_led_data *ild;
+       int ret;
+
+       ild = devm_kzalloc(dev, sizeof(*ild), GFP_KERNEL);
+       if (!ild)
+               return -ENOMEM;
+
+       ret = jnx_i2cs_leds_of_init(dev, ild);
+       if (ret < 0)
+               return ret;
+
+       platform_set_drvdata(pdev, ild);
+
+       return 0;
+}
+
+static int jnx_i2cs_leds_remove(struct platform_device *pdev)
+{
+       struct i2cs_led_data *ild = platform_get_drvdata(pdev);
+       int i;
+
+       for (i = 0; i < ild->num_leds; i++) {
+               devm_led_classdev_unregister(&pdev->dev, &ild->leds[i].lc);

This is redundant.

+               cancel_work_sync(&ild->leds[i].work);
+       }
+
+       return 0;
+}

This function will be redundant after removing work queue.

+static const struct of_device_id jnx_i2cs_leds_match[] = {
+       { .compatible = "jnx,leds-i2cs", },
+       { },
+};
+MODULE_DEVICE_TABLE(of, jnx_i2cs_leds_match);
+
+static struct platform_driver jnx_i2cs_leds_driver = {
+       .driver = {
+               .name  = "leds-i2cs",
+               .of_match_table = jnx_i2cs_leds_match,
+       },
+       .probe = jnx_i2cs_leds_probe,
+       .remove = jnx_i2cs_leds_remove,
+};
+
+module_platform_driver(jnx_i2cs_leds_driver);
+
+MODULE_DESCRIPTION("Juniper Networks I2CS leds driver");
+MODULE_AUTHOR("Georgi Vlaev <gvl...@juniper.net>");
+MODULE_LICENSE("GPL");



--
Best regards,
Jacek Anaszewski
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