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[104.57.184.186]) by smtp.gmail.com with ESMTPSA id p8sm781364oot.29.2020.09.30.15.40.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Sep 2020 15:40:16 -0700 (PDT) From: Bjorn Andersson To: David Airlie , Daniel Vetter , Rob Herring , Andrzej Hajda , Neil Armstrong , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Douglas Anderson Cc: dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org Subject: [PATCH 2/2] drm/bridge: ti-sn65dsi86: Expose backlight controls Date: Wed, 30 Sep 2020 17:35:32 -0500 Message-Id: <20200930223532.77755-3-bjorn.andersson@linaro.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200930223532.77755-1-bjorn.andersson@linaro.org> References: <20200930223532.77755-1-bjorn.andersson@linaro.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org The TI SN65DSI86 can be configured to generate a PWM pulse on GPIO4, to be used to drive a backlight driver. Signed-off-by: Bjorn Andersson --- drivers/gpu/drm/bridge/Kconfig | 1 + drivers/gpu/drm/bridge/ti-sn65dsi86.c | 143 +++++++++++++++++++++++++- 2 files changed, 140 insertions(+), 4 deletions(-) -- 2.28.0 diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig index 43271c21d3fc..eea310bd88e1 100644 --- a/drivers/gpu/drm/bridge/Kconfig +++ b/drivers/gpu/drm/bridge/Kconfig @@ -195,6 +195,7 @@ config DRM_TI_SN65DSI86 select REGMAP_I2C select DRM_PANEL select DRM_MIPI_DSI + select BACKLIGHT_CLASS_DEVICE help Texas Instruments SN65DSI86 DSI to eDP Bridge driver diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c index 5b6e19ecbc84..41e24d0dbd18 100644 --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c @@ -68,6 +68,7 @@ #define SN_GPIO_MUX_OUTPUT 1 #define SN_GPIO_MUX_SPECIAL 2 #define SN_GPIO_MUX_MASK 0x3 +#define SN_GPIO_MUX_SHIFT(gpio) ((gpio) * 2) #define SN_AUX_WDATA_REG(x) (0x64 + (x)) #define SN_AUX_ADDR_19_16_REG 0x74 #define SN_AUX_ADDR_15_8_REG 0x75 @@ -86,6 +87,12 @@ #define SN_ML_TX_MODE_REG 0x96 #define ML_TX_MAIN_LINK_OFF 0 #define ML_TX_NORMAL_MODE BIT(0) +#define SN_PWM_PRE_DIV_REG 0xA0 +#define SN_BACKLIGHT_SCALE_REG 0xA1 +#define SN_BACKLIGHT_REG 0xA3 +#define SN_PWM_CTL_REG 0xA5 +#define SN_PWM_ENABLE BIT(1) +#define SN_PWM_INVERT BIT(0) #define SN_AUX_CMD_STATUS_REG 0xF4 #define AUX_IRQ_STATUS_AUX_RPLY_TOUT BIT(3) #define AUX_IRQ_STATUS_AUX_SHORT BIT(5) @@ -155,6 +162,8 @@ struct ti_sn_bridge { struct gpio_chip gchip; DECLARE_BITMAP(gchip_output, SN_NUM_GPIOS); #endif + u32 brightness; + u32 max_brightness; }; static const struct regmap_range ti_sn_bridge_volatile_ranges[] = { @@ -173,6 +182,18 @@ static const struct regmap_config ti_sn_bridge_regmap_config = { .cache_type = REGCACHE_NONE, }; +static void ti_sn_bridge_read_u16(struct ti_sn_bridge *pdata, + unsigned int reg, u16 *val) +{ + unsigned int high; + unsigned int low; + + regmap_read(pdata->regmap, reg, &low); + regmap_read(pdata->regmap, reg + 1, &high); + + *val = high << 8 | low; +} + static void ti_sn_bridge_write_u16(struct ti_sn_bridge *pdata, unsigned int reg, u16 val) { @@ -180,6 +201,50 @@ static void ti_sn_bridge_write_u16(struct ti_sn_bridge *pdata, regmap_write(pdata->regmap, reg + 1, val >> 8); } +static int ti_sn_backlight_update(struct ti_sn_bridge *pdata) +{ + unsigned int pre_div; + + if (!pdata->max_brightness) + return 0; + + /* Enable PWM on GPIO4 */ + regmap_update_bits(pdata->regmap, SN_GPIO_CTRL_REG, + SN_GPIO_MUX_MASK << SN_GPIO_MUX_SHIFT(4 - 1), + SN_GPIO_MUX_SPECIAL << SN_GPIO_MUX_SHIFT(4 - 1)); + + if (pdata->brightness) { + /* Set max brightness */ + ti_sn_bridge_write_u16(pdata, SN_BACKLIGHT_SCALE_REG, pdata->max_brightness); + + /* Set brightness */ + ti_sn_bridge_write_u16(pdata, SN_BACKLIGHT_REG, pdata->brightness); + + /* + * The PWM frequency is derived from the refclk as: + * PWM_FREQ = REFCLK_FREQ / (PWM_PRE_DIV * BACKLIGHT_SCALE + 1) + * + * A hand wavy estimate based on 12MHz refclk and 500Hz desired + * PWM frequency gives us a pre_div resulting in a PWM + * frequency of between 500 and 1600Hz, depending on the actual + * refclk rate. + * + * One is added to avoid high BACKLIGHT_SCALE values to produce + * a pre_div of 0 - which cancels out the large BACKLIGHT_SCALE + * value. + */ + pre_div = 12000000 / (500 * pdata->max_brightness) + 1; + regmap_write(pdata->regmap, SN_PWM_PRE_DIV_REG, pre_div); + + /* Enable PWM */ + regmap_update_bits(pdata->regmap, SN_PWM_CTL_REG, SN_PWM_ENABLE, SN_PWM_ENABLE); + } else { + regmap_update_bits(pdata->regmap, SN_PWM_CTL_REG, SN_PWM_ENABLE, 0); + } + + return 0; +} + static int __maybe_unused ti_sn_bridge_resume(struct device *dev) { struct ti_sn_bridge *pdata = dev_get_drvdata(dev); @@ -193,7 +258,7 @@ static int __maybe_unused ti_sn_bridge_resume(struct device *dev) gpiod_set_value(pdata->enable_gpio, 1); - return ret; + return ti_sn_backlight_update(pdata); } static int __maybe_unused ti_sn_bridge_suspend(struct device *dev) @@ -1010,7 +1075,7 @@ static int ti_sn_bridge_gpio_direction_input(struct gpio_chip *chip, unsigned int offset) { struct ti_sn_bridge *pdata = gpiochip_get_data(chip); - int shift = offset * 2; + int shift = SN_GPIO_MUX_SHIFT(offset); int ret; if (!test_and_clear_bit(offset, pdata->gchip_output)) @@ -1038,7 +1103,7 @@ static int ti_sn_bridge_gpio_direction_output(struct gpio_chip *chip, unsigned int offset, int val) { struct ti_sn_bridge *pdata = gpiochip_get_data(chip); - int shift = offset * 2; + int shift = SN_GPIO_MUX_SHIFT(offset); int ret; if (test_and_set_bit(offset, pdata->gchip_output)) @@ -1073,12 +1138,17 @@ static const char * const ti_sn_bridge_gpio_names[SN_NUM_GPIOS] = { static int ti_sn_setup_gpio_controller(struct ti_sn_bridge *pdata) { + int ngpio = SN_NUM_GPIOS; int ret; /* Only init if someone is going to use us as a GPIO controller */ if (!of_property_read_bool(pdata->dev->of_node, "gpio-controller")) return 0; + /* If GPIO4 is used for backlight, reduce number of gpios */ + if (pdata->max_brightness) + ngpio--; + pdata->gchip.label = dev_name(pdata->dev); pdata->gchip.parent = pdata->dev; pdata->gchip.owner = THIS_MODULE; @@ -1092,7 +1162,7 @@ static int ti_sn_setup_gpio_controller(struct ti_sn_bridge *pdata) pdata->gchip.set = ti_sn_bridge_gpio_set; pdata->gchip.can_sleep = true; pdata->gchip.names = ti_sn_bridge_gpio_names; - pdata->gchip.ngpio = SN_NUM_GPIOS; + pdata->gchip.ngpio = ngpio; pdata->gchip.base = -1; ret = devm_gpiochip_add_data(pdata->dev, &pdata->gchip, pdata); if (ret) @@ -1159,6 +1229,65 @@ static void ti_sn_bridge_parse_lanes(struct ti_sn_bridge *pdata, pdata->ln_polrs = ln_polrs; } +static int ti_sn_backlight_update_status(struct backlight_device *bl) +{ + struct ti_sn_bridge *pdata = bl_get_data(bl); + int brightness = bl->props.brightness; + + if (bl->props.power != FB_BLANK_UNBLANK || + bl->props.fb_blank != FB_BLANK_UNBLANK || + bl->props.state & BL_CORE_FBBLANK) { + pdata->brightness = 0; + } + + pdata->brightness = brightness; + + return ti_sn_backlight_update(pdata); +} + +static int ti_sn_backlight_get_brightness(struct backlight_device *bl) +{ + struct ti_sn_bridge *pdata = bl_get_data(bl); + u16 val; + + ti_sn_bridge_read_u16(pdata, SN_BACKLIGHT_REG, &val); + + return val; +} + +const struct backlight_ops ti_sn_backlight_ops = { + .update_status = ti_sn_backlight_update_status, + .get_brightness = ti_sn_backlight_get_brightness, +}; + +static int ti_sn_backlight_init(struct ti_sn_bridge *pdata) +{ + struct backlight_properties props = {}; + struct backlight_device *bl; + struct device *dev = pdata->dev; + struct device_node *np = dev->of_node; + int ret; + + ret = of_property_read_u32(np, "ti,backlight-scale", &pdata->max_brightness); + if (ret == -EINVAL) { + return 0; + } else if (ret || pdata->max_brightness >= 0xffff) { + DRM_ERROR("invalid max-brightness\n"); + return -EINVAL; + } + + props.type = BACKLIGHT_RAW; + props.max_brightness = pdata->max_brightness; + bl = devm_backlight_device_register(dev, "sn65dsi86", dev, pdata, + &ti_sn_backlight_ops, &props); + if (IS_ERR(bl)) { + DRM_ERROR("failed to register backlight device\n"); + return PTR_ERR(bl); + } + + return 0; +} + static int ti_sn_bridge_probe(struct i2c_client *client, const struct i2c_device_id *id) { @@ -1224,6 +1353,12 @@ static int ti_sn_bridge_probe(struct i2c_client *client, pm_runtime_enable(pdata->dev); + ret = ti_sn_backlight_init(pdata); + if (ret) { + pm_runtime_disable(pdata->dev); + return ret; + } + ret = ti_sn_setup_gpio_controller(pdata); if (ret) { pm_runtime_disable(pdata->dev);