Re: [PATCH 4/4] video: add support for Solomon SSD1307 OLED controller family

[Bastian Stender <bst@pengutronix.de>]

On 02/27/2017 11:08 AM, Sascha Hauer wrote:
> On Fri, Feb 24, 2017 at 03:25:01PM +0100, Bastian Stender wrote:
>> It was ported from linux v4.10. Like the kernel driver only
>> communication via I2C is supported.
>>
>> It has only been tested with a SSD1306 and a 96x16 OLED display:
>>
>> 	&i2c0 {
>> 		status = "okay";
>>
>> 		ssd1306: oled@3c {
>> 			compatible = "solomon,ssd1306fb-i2c";
>> 			reg = <0x3c>;
>> 			reset-gpios = <&gpio1 1 0>;
>> 			solomon,height = <16>;
>> 			solomon,width = <96>;
>> 			solomon,page-offset = <0>;
>> 			solomon,com-invdir;
>> 			solomon,com-seq;
>> 		};
>>
>> Signed-off-by: Bastian Stender <bst@pengutronix.de>
>> ---
>>  drivers/video/Kconfig     |   4 +
>>  drivers/video/Makefile    |   1 +
>>  drivers/video/ssd1307fb.c | 569 ++++++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 574 insertions(+)
>>  create mode 100644 drivers/video/ssd1307fb.c
>>
>> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
>> index 8f31f5af74..50a876acb1 100644
>> --- a/drivers/video/Kconfig
>> +++ b/drivers/video/Kconfig
>> @@ -12,6 +12,10 @@ config FRAMEBUFFER_CONSOLE
>>  	select FONTS
>>  	prompt "framebuffer console support"
>>
>> +config DRIVER_VIDEO_FB_SSD1307
>> +	bool "Solomon SSD1307 framebuffer support"
>> +	depends on PWM && I2C && GPIOLIB
>> +
>>  config VIDEO_VPL
>>  	depends on OFTREE
>>  	bool
>> diff --git a/drivers/video/Makefile b/drivers/video/Makefile
>> index 1bf2e1f3ca..e23c9c37b6 100644
>> --- a/drivers/video/Makefile
>> +++ b/drivers/video/Makefile
>> @@ -21,3 +21,4 @@ obj-$(CONFIG_DRIVER_VIDEO_OMAP) += omap.o
>>  obj-$(CONFIG_DRIVER_VIDEO_BCM283X) += bcm2835.o
>>  obj-$(CONFIG_DRIVER_VIDEO_SIMPLEFB) += simplefb.o
>>  obj-$(CONFIG_DRIVER_VIDEO_IMX_IPUV3) += imx-ipu-v3/
>> +obj-$(CONFIG_DRIVER_VIDEO_FB_SSD1307) += ssd1307fb.o
>> diff --git a/drivers/video/ssd1307fb.c b/drivers/video/ssd1307fb.c
>> new file mode 100644
>> index 0000000000..0dfdcc2232
>> --- /dev/null
>> +++ b/drivers/video/ssd1307fb.c
>> @@ -0,0 +1,569 @@
>> +/*
>> + * Driver for the Solomon SSD1307 OLED controller family
>> + *
>> + * Supports:
>> + *	- SSD1305 (untested)
>> + *	- SSD1306
>> + *	- SSD1307 (untested)
>> + *	- SSD1309 (untested)
>> + *
>> + * Copyright 2012 Maxime Ripard <maxime.ripard@free-electrons.com>, Free Electrons
>> + *
>> + * Ported to barebox from linux v4.10
>> + * Copyright (C) 2017 Pengutronix, Bastian Stender <kernel@pengutronix.de>
>> + *
>> + * Licensed under the GPLv2 or later.
>> + */
>> +
>> +#include <common.h>
>> +#include <init.h>
>> +#include <fb.h>
>> +#include <i2c/i2c.h>
>> +#include <of_device.h>
>> +#include <gpio.h>
>> +#include <of_gpio.h>
>> +#include <printk.h>
>> +
>> +#define SSD1307FB_DATA			0x40
>> +#define SSD1307FB_COMMAND		0x80
>> +
>> +#define SSD1307FB_SET_ADDRESS_MODE	0x20
>> +#define SSD1307FB_SET_ADDRESS_MODE_HORIZONTAL	(0x00)
>> +#define SSD1307FB_SET_ADDRESS_MODE_VERTICAL	(0x01)
>> +#define SSD1307FB_SET_ADDRESS_MODE_PAGE		(0x02)
>> +#define SSD1307FB_SET_COL_RANGE		0x21
>> +#define SSD1307FB_SET_PAGE_RANGE	0x22
>> +#define SSD1307FB_CONTRAST		0x81
>> +#define	SSD1307FB_CHARGE_PUMP		0x8d
>> +#define SSD1307FB_SEG_REMAP_ON		0xa1
>> +#define SSD1307FB_DISPLAY_OFF		0xae
>> +#define SSD1307FB_SET_MULTIPLEX_RATIO	0xa8
>> +#define SSD1307FB_DISPLAY_ON		0xaf
>> +#define SSD1307FB_START_PAGE_ADDRESS	0xb0
>> +#define SSD1307FB_SET_DISPLAY_OFFSET	0xd3
>> +#define	SSD1307FB_SET_CLOCK_FREQ	0xd5
>> +#define	SSD1307FB_SET_PRECHARGE_PERIOD	0xd9
>> +#define	SSD1307FB_SET_COM_PINS_CONFIG	0xda
>> +#define	SSD1307FB_SET_VCOMH		0xdb
>
> please consistently use spaces after #define

Will do.

>
>> +
>> +struct ssd1307fb_par;
>
> Unnecessary.

Ok.

>
>> +
>> +struct ssd1307fb_deviceinfo {
>> +	u32 default_vcomh;
>> +	u32 default_dclk_div;
>> +	u32 default_dclk_frq;
>> +	int need_chargepump;
>> +};
>> +
>
> [...]
>
>> +static int ssd1307fb_probe(struct device_d *dev)
>> +{
>> +	struct i2c_client *client = to_i2c_client(dev);
>> +	struct fb_info *info;
>> +	struct device_node *node = dev->device_node;
>> +	const struct of_device_id *match =
>> +		of_match_node(ssd1307fb_of_match, dev->device_node);
>> +	u32 vmem_size;
>> +	struct ssd1307fb_par *par;
>> +	struct ssd1307fb_array *array;
>> +	u8 *vmem;
>> +	int ret;
>> +	int i, j;
>> +
>> +	if (!node) {
>> +		dev_err(&client->dev, "No device tree data found!\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	info = xzalloc(sizeof(struct fb_info));
>> +	if (!info) {
>> +		dev_err(&client->dev, "Couldn't allocate framebuffer.\n");
>> +		return -ENOMEM;
>> +	}
>
> xzalloc always returns succesfully, no need to check.

Ok.

>
>> +
>> +	par = info->priv;
>> +	par->info = info;
>> +	par->client = client;
>> +
>> +	par->device_info = (struct ssd1307fb_deviceinfo *)match->data;
>> +
>> +	par->reset = of_get_named_gpio(node,
>> +					 "reset-gpios", 0);
>> +	if (!gpio_is_valid(par->reset)) {
>> +		dev_err(&client->dev,
>> +			"Couldn't get named gpio 'reset-gpios' %d.\n",
>> +			par->reset);
>> +		ret = par->reset;
>> +		goto fb_alloc_error;
>> +	}
>
> Is this gpio really mandatory?


This is the corresponding snippet from the kernel in 
drivers/video/fbdev/ssd1307fb.c, line 564 ff. (v4.10):

     par->reset = of_get_named_gpio(client->dev.of_node,
                                  "reset-gpios", 0);
     if (!gpio_is_valid(par->reset)) {
         ret = -EINVAL;
         goto fb_alloc_error;
     }

"reset-gpios" is one of the required properties, see

   Documentation/devicetree/bindings/display/ssd1307fb.txt

or in barebox:

   dts/Bindings/display/ssd1307fb.txt

>
>> +
>> +	if (of_property_read_u32(node, "solomon,width", &par->width))
>> +		par->width = 96;
>> +
>> +	if (of_property_read_u32(node, "solomon,height", &par->height))
>> +		par->height = 16;
>
> These defaults only work for you. You should bail out with an error if
> the devicetree does not contain values for these instead.

This part was ported 1:1 from linux. As solomon,width and solomon,height 
are required properties also, should I bail out nonetheless?

Regards,
Bastian

-- 
Pengutronix e.K.
Industrial Linux Solutions
http://www.pengutronix.de/
Peiner Str. 6-8, 31137 Hildesheim, Germany
Amtsgericht Hildesheim, HRA 2686

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