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SubjectRe: [PATCH 2/8] fbdev: ssd1307fb: Unify init code and make controller configurable from device tree
Hi,

On Fri, Feb 06, 2015 at 11:28:08PM +0100, niederp@physik.uni-kl.de wrote:
> From: Thomas Niederprüm <niederp@physik.uni-kl.de>
>
> This patches unifies the init code for the ssd130X chips and
> adds device tree bindings to describe the hardware configuration
> of the used controller. This gets rid of the magic bit values
> used in the init code so far.
>
> Signed-off-by: Thomas Niederprüm <niederp@physik.uni-kl.de>
> ---
> .../devicetree/bindings/video/ssd1307fb.txt | 11 +
> drivers/video/fbdev/ssd1307fb.c | 243 ++++++++++++++-------
> 2 files changed, 174 insertions(+), 80 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/video/ssd1307fb.txt b/Documentation/devicetree/bindings/video/ssd1307fb.txt
> index 7a12542..1230f68 100644
> --- a/Documentation/devicetree/bindings/video/ssd1307fb.txt
> +++ b/Documentation/devicetree/bindings/video/ssd1307fb.txt
> @@ -15,6 +15,17 @@ Required properties:
>
> Optional properties:
> - reset-active-low: Is the reset gpio is active on physical low?
> + - solomon,segment-remap: Invert the order of data column to segment mapping
> + - solomon,offset: Map the display start line to one of COM0 - COM63
> + - solomon,contrast: Set initial contrast of the display
> + - solomon,prechargep1: Set the duration of the precharge period phase1
> + - solomon,prechargep2: Set the duration of the precharge period phase2
> + - solomon,com-alt: Enable/disable alternate COM pin configuration
> + - solomon,com-lrremap: Enable/disable left-right remap of COM pins
> + - solomon,com-invdir: Invert COM scan direction
> + - solomon,vcomh: Set VCOMH regulator voltage
> + - solomon,dclk-div: Set display clock divider
> + - solomon,dclk-frq: Set display clock frequency

I'm sorry, but this is the wrong approach, for at least two reasons:
you broke all existing users of that driver, which is a clear no-go,
and the DT itself should not contain any direct mapping of the
registers.


>
> [0]: Documentation/devicetree/bindings/pwm/pwm.txt
>
> diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
> index 3d6611f..4f435aa 100644
> --- a/drivers/video/fbdev/ssd1307fb.c
> +++ b/drivers/video/fbdev/ssd1307fb.c
> @@ -16,6 +16,9 @@
> #include <linux/pwm.h>
> #include <linux/delay.h>
>
> +#define DEVID_SSD1306 6
> +#define DEVID_SSD1307 7
> +
> #define SSD1307FB_DATA 0x40
> #define SSD1307FB_COMMAND 0x80
>
> @@ -40,20 +43,33 @@
>
> struct ssd1307fb_par;
>
> -struct ssd1307fb_ops {
> - int (*init)(struct ssd1307fb_par *);
> - int (*remove)(struct ssd1307fb_par *);
> +struct ssd1307fb_deviceinfo {
> + int device_id;
> + u32 default_vcomh;
> + u32 default_dclk_div;
> + u32 default_dclk_frq;
> };
>
> struct ssd1307fb_par {
> + u32 com_alt;
> + u32 com_invdir;
> + u32 com_lrremap;
> + 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 offset;
> u32 page_offset;
> + u32 prechargep1;
> + u32 prechargep2;
> struct pwm_device *pwm;
> u32 pwm_period;
> int reset;
> + u32 seg_remap;
> + u32 vcomh;
> u32 width;
> };
>
> @@ -254,127 +270,151 @@ 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->device_id == DEVID_SSD1307) {
> + 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);
> - 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;
>
> /* Set multiplex ratio value */
> ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_MULTIPLEX_RATIO);
> - ret = ret & ssd1307fb_write_cmd(par->client, par->height - 1);
> + if (ret < 0)
> + return ret;
> +
> + ret = ssd1307fb_write_cmd(par->client, par->height - 1);
> if (ret < 0)
> return ret;
>
> /* set display offset value */
> ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_DISPLAY_OFFSET);
> - ret = ssd1307fb_write_cmd(par->client, 0x20);
> + if (ret < 0)
> + return ret;
> +
> + ret = ssd1307fb_write_cmd(par->client, par->offset);
> if (ret < 0)
> return ret;
>
> /* Set clock frequency */
> + dclk = (par->dclk_div & 0xf) | (par->dclk_frq & 0xf) << 4;
> ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_CLOCK_FREQ);
> - ret = ret & ssd1307fb_write_cmd(par->client, 0xf0);
> if (ret < 0)
> return ret;
>
> - /* Set precharge period in number of ticks from the internal clock */
> + ret = ssd1307fb_write_cmd(par->client, dclk);
> + if (ret < 0)
> + return ret;
> +
> + /* Set precharge period in number of ticks from the internal clock*/
> + precharge = (par->prechargep1 & 0xf) | (par->prechargep2 & 0xf) << 4;
> ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_PRECHARGE_PERIOD);
> - ret = ret & ssd1307fb_write_cmd(par->client, 0x22);
> + if (ret < 0)
> + return ret;
> +
> + ret = ssd1307fb_write_cmd(par->client, precharge);
> if (ret < 0)
> return ret;
>
> /* Set COM pins configuration */
> + compins = 0x02 | (par->com_alt & 0x1) << 4
> + | (par->com_lrremap & 0x1) << 5;
> ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_COM_PINS_CONFIG);
> - ret = ret & ssd1307fb_write_cmd(par->client, 0x22);
> + if (ret < 0)
> + return ret;
> +
> + ret = ssd1307fb_write_cmd(par->client, compins);
> if (ret < 0)
> return ret;
>
> /* Set VCOMH */
> ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_VCOMH);
> - ret = ret & ssd1307fb_write_cmd(par->client, 0x49);
> if (ret < 0)
> return ret;
>
> - /* Turn on the DC-DC Charge Pump */
> - ret = ssd1307fb_write_cmd(par->client, SSD1307FB_CHARGE_PUMP);
> - ret = ret & ssd1307fb_write_cmd(par->client, 0x14);
> + ret = ssd1307fb_write_cmd(par->client, par->vcomh);
> if (ret < 0)
> return ret;
>
> + if (par->device_info->device_id == DEVID_SSD1306) {
> + /* 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;
> + };
> +
> /* Switch to horizontal addressing mode */
> ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_ADDRESS_MODE);
> - ret = ret & ssd1307fb_write_cmd(par->client,
> + if (ret < 0)
> + return ret;
> +
> + ret = ssd1307fb_write_cmd(par->client,
> SSD1307FB_SET_ADDRESS_MODE_HORIZONTAL);
> if (ret < 0)
> return ret;
>
> + /* Set column range */
> ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_COL_RANGE);
> - ret = ret & ssd1307fb_write_cmd(par->client, 0x0);
> - ret = ret & ssd1307fb_write_cmd(par->client, par->width - 1);
> if (ret < 0)
> return ret;
>
> + ret = ssd1307fb_write_cmd(par->client, 0x0);
> + if (ret < 0)
> + return ret;
> +
> + ret = ssd1307fb_write_cmd(par->client, par->width - 1);
> + if (ret < 0)
> + return ret;
> +
> + /* Set page range */
> ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_PAGE_RANGE);
> - ret = ret & ssd1307fb_write_cmd(par->client, 0x0);
> - ret = ret & ssd1307fb_write_cmd(par->client,
> + if (ret < 0)
> + return ret;
> +
> + ret = ssd1307fb_write_cmd(par->client, 0x0);
> + if (ret < 0)
> + return ret;
> +
> + ret = ssd1307fb_write_cmd(par->client,
> par->page_offset + (par->height / 8) - 1);
> if (ret < 0)
> return ret;
> @@ -387,18 +427,28 @@ 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 = {
> + .device_id = DEVID_SSD1306,
> + .default_vcomh = 0x20,
> + .default_dclk_div = 0,
> + .default_dclk_frq = 8,
> +};
> +
> +static struct ssd1307fb_deviceinfo ssd1307fb_ssd1307_deviceinfo = {
> + .device_id = DEVID_SSD1307,
> + .default_vcomh = 0x20,
> + .default_dclk_div = 1,
> + .default_dclk_frq = 12,
> };
>
> 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,
> },
> {},
> };
> @@ -429,8 +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);
> @@ -449,8 +499,40 @@ static int ssd1307fb_probe(struct i2c_client *client,
> par->page_offset = 1;
>
> vmem_size = par->width * par->height / 8;
> + if (of_property_read_u32(node, "solomon,segment-remap", &par->seg_remap))
> + par->seg_remap = 0;
> +
> + if (of_property_read_u32(node, "solomon,offset", &par->offset))
> + par->offset = 0;
> +
> + if (of_property_read_u32(node, "solomon,contrast", &par->contrast))
> + par->contrast = 128;
> +
> + 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 = 2;
> +
> + if (of_property_read_u32(node, "solomon,com-alt", &par->com_alt))
> + par->com_alt = 1;
> +
> + if (of_property_read_u32(node, "solomon,com-lrremap", &par->com_lrremap))
> + par->com_lrremap = 0;
> +
> + if (of_property_read_u32(node, "solomon,com-invdir", &par->com_invdir))
> + par->com_invdir = 0;
> +
> + if (of_property_read_u32(node, "solomon,vcomh", &par->vcomh))
> + par->vcomh = par->device_info->default_vcomh;
>
> vmem = devm_kzalloc(&client->dev, vmem_size, GFP_KERNEL);
> + if (of_property_read_u32(node, "solomon,dclk-div", &par->dclk_div))
> + par->dclk_div = par->device_info->default_dclk_div;
> +
> + if (of_property_read_u32(node, "solomon,dclk-frq", &par->dclk_frq))
> + par->dclk_frq = par->device_info->default_dclk_frq;
> +
> if (!vmem) {
> dev_err(&client->dev, "Couldn't allocate graphical memory.\n");
> ret = -ENOMEM;
> @@ -499,11 +581,9 @@ 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) {
> @@ -516,8 +596,10 @@ 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->device_id == DEVID_SSD1307) {
> + pwm_disable(par->pwm);
> + pwm_put(par->pwm);
> + };
> reset_oled_error:
> fb_deferred_io_cleanup(info);
> fb_alloc_error:
> @@ -531,11 +613,12 @@ 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->device_id == DEVID_SSD1307) {
> + pwm_disable(par->pwm);
> + pwm_put(par->pwm);
> + };
> fb_deferred_io_cleanup(info);
> framebuffer_release(info);
> -
> return 0;
> }
>
> --
> 2.1.1
>

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