Re: [PATCHv5 04/11] fbdev: ssd1307fb: Unify init code and obtain hw specific bits from DT

[Maxime Ripard <maxime.ripard@free-electrons.com>]

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On Tue, Mar 24, 2015 at 10:23:51PM +0100, Thomas Niederprüm wrote:
> The 130X controllers are very similar from the configuration point of view.
> The configuration registers for the SSD1305/6/7 are bit identical (except the
> the VHCOM register and the the default values for clock setup register). This
> patch unifies the init code of the controller and adds hardware specific
> properties to DT that are needed to correctly initialize the device.
> 
> The SSD130X can be wired to the OLED panel in various ways. Even for the
> same controller this wiring can differ from one display module to another
> and can not be probed by software. The added DT properties reflect these
> hardware decisions of the display module manufacturer.
> The 'com-sequential', 'com-lrremap' and 'com-invdir' values define different
> possibilities for the COM signals pin configuration and readout direction
> of the video memory. The 'segment-no-remap' allows the inversion of the
> memory-to-pin mapping ultimately inverting the order of the controllers
> output pins. The 'prechargepX' values need to be adapted according to the
> capacitance of the OLEDs pixel cells.
> 
> So far these hardware specific bits are hard coded in the init code, making
> the driver usable only for one certain wiring of the controller. This patch
> makes the driver usable with all possible hardware setups, given a valid hw
> description in DT. If these values are not set in DT the default values,
> as they are set in the ssd1307 init code right now, are used. This implies
> that without the corresponding DT property "segment-no-remap" the segment
> remap of the ssd130X controller gets activated. Even though this is not the
> default behaviour according to the datasheet it maintains backward
> compatibility with older DTBs.
> 
> Note that the SSD1306 does not seem to be using the configuration written to
> the registers at all. Therefore this patch does not try to maintain these
> values without changes in DT. For reference an example is added to the DT
> bindings documentation that reproduces the configuration that is set in the
> current init code.
> 
> Signed-off-by: Thomas Niederprüm <niederp@physik.uni-kl.de>
> ---
>  .../devicetree/bindings/video/ssd1307fb.txt        |  21 +++
>  drivers/video/fbdev/ssd1307fb.c                    | 192 ++++++++++++---------
>  2 files changed, 134 insertions(+), 79 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/video/ssd1307fb.txt b/Documentation/devicetree/bindings/video/ssd1307fb.txt
> index 7a12542..637690f 100644
> --- a/Documentation/devicetree/bindings/video/ssd1307fb.txt
> +++ b/Documentation/devicetree/bindings/video/ssd1307fb.txt
> @@ -15,6 +15,16 @@ Required properties:
>  
>  Optional properties:
>    - reset-active-low: Is the reset gpio is active on physical low?
> +  - solomon,segment-no-remap: Display needs normal (non-inverted) data column
> +                              to segment mapping
> +  - solomon,com-sequential: Display uses sequential COM pin configuration
> +  - solomon,com-lrremap: Display uses left-right COM pin remap
> +  - solomon,com-invdir: Display uses inverted COM pin scan direction
> +  - solomon,com-offset: Number of the COM pin wired to the first display line
> +  - solomon,prechargep1: Length of deselect period (phase 1) in clock cycles.
> +  - solomon,prechargep2: Length of precharge period (phase 2) in clock cycles.
> +                         This needs to be the higher, the higher the capacitance
> +                         of the OLED's pixels is
>  
>  [0]: Documentation/devicetree/bindings/pwm/pwm.txt
>  
> @@ -26,3 +36,14 @@ ssd1307: oled@3c {
>          reset-gpios = <&gpio2 7>;
>          reset-active-low;
>  };
> +
> +ssd1306: oled@3c {
> +        compatible = "solomon,ssd1306fb-i2c";
> +        reg = <0x3c>;
> +        pwms = <&pwm 4 3000>;
> +        reset-gpios = <&gpio2 7>;
> +        reset-active-low;
> +        solomon,com-lrremap;
> +        solomon,com-invdir;
> +        solomon,com-offset = <32>;
> +};
> diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
> index 8d34c56..d16aad4 100644
> --- a/drivers/video/fbdev/ssd1307fb.c
> +++ b/drivers/video/fbdev/ssd1307fb.c
> @@ -40,20 +40,34 @@
>  
>  struct ssd1307fb_par;
>  
> -struct ssd1307fb_ops {
> -	int (*init)(struct ssd1307fb_par *);
> -	int (*remove)(struct ssd1307fb_par *);
> +struct ssd1307fb_deviceinfo {
> +	u32 default_vcomh;
> +	u32 default_dclk_div;
> +	u32 default_dclk_frq;
> +	int need_pwm;
> +	int need_chargepump;
>  };
>  
>  struct ssd1307fb_par {
> +	u32 com_invdir;
> +	u32 com_lrremap;
> +	u32 com_offset;
> +	u32 com_seq;
> +	u32 contrast;
> +	u32 dclk_div;
> +	u32 dclk_frq;
> +	struct ssd1307fb_deviceinfo *device_info;
>  	struct i2c_client *client;
>  	u32 height;
>  	struct fb_info *info;
> -	struct ssd1307fb_ops *ops;
>  	u32 page_offset;
> +	u32 prechargep1;
> +	u32 prechargep2;
>  	struct pwm_device *pwm;
>  	u32 pwm_period;
>  	int reset;
> +	u32 seg_remap;
> +	u32 vcomh;
>  	u32 width;
>  };
>  
> @@ -254,69 +268,46 @@ static struct fb_deferred_io ssd1307fb_defio = {
>  	.deferred_io	= ssd1307fb_deferred_io,
>  };
>  
> -static int ssd1307fb_ssd1307_init(struct ssd1307fb_par *par)
> +static int ssd1307fb_init(struct ssd1307fb_par *par)
>  {
>  	int ret;
> +	u32 precharge, dclk, com_invdir, compins;
>  
> -	par->pwm = pwm_get(&par->client->dev, NULL);
> -	if (IS_ERR(par->pwm)) {
> -		dev_err(&par->client->dev, "Could not get PWM from device tree!\n");
> -		return PTR_ERR(par->pwm);
> -	}
> -
> -	par->pwm_period = pwm_get_period(par->pwm);
> -	/* Enable the PWM */
> -	pwm_config(par->pwm, par->pwm_period / 2, par->pwm_period);
> -	pwm_enable(par->pwm);
> -
> -	dev_dbg(&par->client->dev, "Using PWM%d with a %dns period.\n",
> -		par->pwm->pwm, par->pwm_period);
> -
> -	/* Map column 127 of the OLED to segment 0 */
> -	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SEG_REMAP_ON);
> -	if (ret < 0)
> -		return ret;
> -
> -	/* Turn on the display */
> -	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_DISPLAY_ON);
> -	if (ret < 0)
> -		return ret;
> -
> -	return 0;
> -}
> -
> -static int ssd1307fb_ssd1307_remove(struct ssd1307fb_par *par)
> -{
> -	pwm_disable(par->pwm);
> -	pwm_put(par->pwm);
> -	return 0;
> -}
> +	if (par->device_info->need_pwm) {
> +		par->pwm = pwm_get(&par->client->dev, NULL);
> +		if (IS_ERR(par->pwm)) {
> +			dev_err(&par->client->dev, "Could not get PWM from device tree!\n");
> +			return PTR_ERR(par->pwm);
> +		}
>  
> -static struct ssd1307fb_ops ssd1307fb_ssd1307_ops = {
> -	.init	= ssd1307fb_ssd1307_init,
> -	.remove	= ssd1307fb_ssd1307_remove,
> -};
> +		par->pwm_period = pwm_get_period(par->pwm);
> +		/* Enable the PWM */
> +		pwm_config(par->pwm, par->pwm_period / 2, par->pwm_period);
> +		pwm_enable(par->pwm);
>  
> -static int ssd1307fb_ssd1306_init(struct ssd1307fb_par *par)
> -{
> -	int ret;
> +		dev_dbg(&par->client->dev, "Using PWM%d with a %dns period.\n",
> +			par->pwm->pwm, par->pwm_period);
> +	};
>  
>  	/* Set initial contrast */
>  	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_CONTRAST);
>  	if (ret < 0)
>  		return ret;
>  
> -	ret = ssd1307fb_write_cmd(par->client, 0x7f);
> -	if (ret < 0)
> -		return ret;
> -
> -	/* Set COM direction */
> -	ret = ssd1307fb_write_cmd(par->client, 0xc8);
> +	ret = ssd1307fb_write_cmd(par->client, par->contrast);
>  	if (ret < 0)
>  		return ret;
>  
>  	/* Set segment re-map */
> -	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SEG_REMAP_ON);
> +	if (par->seg_remap) {
> +		ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SEG_REMAP_ON);
> +		if (ret < 0)
> +			return ret;
> +	};
> +
> +	/* Set COM direction */
> +	com_invdir = 0xc0 | (par->com_invdir & 0xf) << 3;
> +	ret = ssd1307fb_write_cmd(par->client,  com_invdir);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -334,7 +325,7 @@ static int ssd1307fb_ssd1306_init(struct ssd1307fb_par *par)
>  	if (ret < 0)
>  		return ret;
>  
> -	ret = ssd1307fb_write_cmd(par->client, 0x20);
> +	ret = ssd1307fb_write_cmd(par->client, par->com_offset);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -343,7 +334,8 @@ static int ssd1307fb_ssd1306_init(struct ssd1307fb_par *par)
>  	if (ret < 0)
>  		return ret;
>  
> -	ret = ssd1307fb_write_cmd(par->client, 0xf0);
> +	dclk = (par->dclk_div & 0xf) | (par->dclk_frq & 0xf) << 4;
> +	ret = ssd1307fb_write_cmd(par->client, dclk);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -352,7 +344,8 @@ static int ssd1307fb_ssd1306_init(struct ssd1307fb_par *par)
>  	if (ret < 0)
>  		return ret;
>  
> -	ret = ssd1307fb_write_cmd(par->client, 0x22);
> +	precharge = (par->prechargep1 & 0xf) | (par->prechargep2 & 0xf) << 4;
> +	ret = ssd1307fb_write_cmd(par->client, precharge);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -361,7 +354,9 @@ static int ssd1307fb_ssd1306_init(struct ssd1307fb_par *par)
>  	if (ret < 0)
>  		return ret;
>  
> -	ret = ssd1307fb_write_cmd(par->client, 0x22);
> +	compins = 0x02 | (!par->com_seq & 0x1) << 4
> +				   | (par->com_lrremap & 0x1) << 5;
> +	ret = ssd1307fb_write_cmd(par->client, compins);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -370,18 +365,20 @@ static int ssd1307fb_ssd1306_init(struct ssd1307fb_par *par)
>  	if (ret < 0)
>  		return ret;
>  
> -	ret = ssd1307fb_write_cmd(par->client, 0x49);
> +	ret = ssd1307fb_write_cmd(par->client, par->vcomh);
>  	if (ret < 0)
>  		return ret;
>  
> -	/* Turn on the DC-DC Charge Pump */
> -	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_CHARGE_PUMP);
> -	if (ret < 0)
> -		return ret;
> +	if (par->device_info->need_chargepump) {
> +		/* Turn on the DC-DC Charge Pump */
> +		ret = ssd1307fb_write_cmd(par->client, SSD1307FB_CHARGE_PUMP);
> +		if (ret < 0)
> +			return ret;
>  
> -	ret = ssd1307fb_write_cmd(par->client, 0x14);
> -	if (ret < 0)
> -		return ret;
> +		ret = ssd1307fb_write_cmd(par->client, 0x14);
> +		if (ret < 0)
> +			return ret;
> +	};
>  
>  	/* Switch to horizontal addressing mode */
>  	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_ADDRESS_MODE);
> @@ -393,6 +390,7 @@ static int ssd1307fb_ssd1306_init(struct ssd1307fb_par *par)
>  	if (ret < 0)
>  		return ret;
>  
> +	/* Set column range */
>  	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_COL_RANGE);
>  	if (ret < 0)
>  		return ret;
> @@ -405,6 +403,7 @@ static int ssd1307fb_ssd1306_init(struct ssd1307fb_par *par)
>  	if (ret < 0)
>  		return ret;
>  
> +	/* Set page range */
>  	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_PAGE_RANGE);
>  	if (ret < 0)
>  		return ret;
> @@ -426,18 +425,30 @@ static int ssd1307fb_ssd1306_init(struct ssd1307fb_par *par)
>  	return 0;
>  }
>  
> -static struct ssd1307fb_ops ssd1307fb_ssd1306_ops = {
> -	.init	= ssd1307fb_ssd1306_init,
> +static struct ssd1307fb_deviceinfo ssd1307fb_ssd1306_deviceinfo = {
> +	.default_vcomh = 0x20,
> +	.default_dclk_div = 0,

A division by 0 ?

> +	.default_dclk_frq = 8,
> +	.need_pwm = 0,

You don't need to declare this field, its value will already be
initialized to 0.

> +	.need_chargepump = 1,
> +};
> +
> +static struct ssd1307fb_deviceinfo ssd1307fb_ssd1307_deviceinfo = {
> +	.default_vcomh = 0x20,
> +	.default_dclk_div = 1,
> +	.default_dclk_frq = 12,
> +	.need_pwm = 1,
> +	.need_chargepump = 0,
>  };

Same thing here.

>  
>  static const struct of_device_id ssd1307fb_of_match[] = {
>  	{
>  		.compatible = "solomon,ssd1306fb-i2c",
> -		.data = (void *)&ssd1307fb_ssd1306_ops,
> +		.data = (void *)&ssd1307fb_ssd1306_deviceinfo,
>  	},
>  	{
>  		.compatible = "solomon,ssd1307fb-i2c",
> -		.data = (void *)&ssd1307fb_ssd1307_ops,
> +		.data = (void *)&ssd1307fb_ssd1307_deviceinfo,
>  	},
>  	{},
>  };
> @@ -468,8 +479,8 @@ static int ssd1307fb_probe(struct i2c_client *client,
>  	par->info = info;
>  	par->client = client;
>  
> -	par->ops = (struct ssd1307fb_ops *)of_match_device(ssd1307fb_of_match,
> -							   &client->dev)->data;
> +	par->device_info = (struct ssd1307fb_deviceinfo *)of_match_device(
> +			ssd1307fb_of_match, &client->dev)->data;
>  
>  	par->reset = of_get_named_gpio(client->dev.of_node,
>  					 "reset-gpios", 0);
> @@ -487,6 +498,27 @@ static int ssd1307fb_probe(struct i2c_client *client,
>  	if (of_property_read_u32(node, "solomon,page-offset", &par->page_offset))
>  		par->page_offset = 1;
>  
> +	if (of_property_read_u32(node, "solomon,com-offset", &par->com_offset))
> +		par->com_offset = 0;
> +
> +	if (of_property_read_u32(node, "solomon,prechargep1", &par->prechargep1))
> +		par->prechargep1 = 2;
> +
> +	if (of_property_read_u32(node, "solomon,prechargep2", &par->prechargep2))
> +		par->prechargep2 = 0;
> +
> +	par->seg_remap = !of_property_read_bool(node, "solomon,segment-no-remap");
> +	par->com_seq = of_property_read_bool(node, "solomon,com-sequential");
> +	par->com_lrremap = of_property_read_bool(node, "solomon,com-lrremap");
> +	par->com_invdir = of_property_read_bool(node, "solomon,com-invdir");
> +
> +	par->contrast = 127;
> +	par->vcomh = par->device_info->default_vcomh;
> +
> +	/* Setup display timing */
> +	par->dclk_div = par->device_info->default_dclk_div;
> +	par->dclk_frq = par->device_info->default_dclk_frq;
> +
>  	vmem_size = par->width * par->height / 8;
>  
>  	vmem = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
> @@ -539,11 +571,9 @@ static int ssd1307fb_probe(struct i2c_client *client,
>  	gpio_set_value(par->reset, 1);
>  	udelay(4);
>  
> -	if (par->ops->init) {
> -		ret = par->ops->init(par);
> -		if (ret)
> -			goto reset_oled_error;
> -	}
> +	ret = ssd1307fb_init(par);
> +	if (ret)
> +		goto reset_oled_error;
>  
>  	ret = register_framebuffer(info);
>  	if (ret) {
> @@ -556,8 +586,10 @@ static int ssd1307fb_probe(struct i2c_client *client,
>  	return 0;
>  
>  panel_init_error:
> -	if (par->ops->remove)
> -		par->ops->remove(par);
> +	if (par->device_info->need_pwm) {
> +		pwm_disable(par->pwm);
> +		pwm_put(par->pwm);
> +	};
>  reset_oled_error:
>  	fb_deferred_io_cleanup(info);
>  fb_alloc_error:
> @@ -571,8 +603,10 @@ static int ssd1307fb_remove(struct i2c_client *client)
>  	struct ssd1307fb_par *par = info->par;
>  
>  	unregister_framebuffer(info);
> -	if (par->ops->remove)
> -		par->ops->remove(par);
> +	if (par->device_info->need_pwm) {
> +		pwm_disable(par->pwm);
> +		pwm_put(par->pwm);
> +	};
>  	fb_deferred_io_cleanup(info);
>  	__free_pages(__va(info->fix.smem_start), get_order(info->fix.smem_len));
>  	framebuffer_release(info);
> -- 
> 2.3.0
> 

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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