dt-bindings: pinctrl: Add MSM8976 driver bindings and documentation

Add the documentation for this new driver for pin configuration
with the pinctrl framework on MSM8976/56 and its APQ variants.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: AngeloGioacchino Del Regno <[e-mail]>
Reviewed-by: Bjorn Andersson <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

Documentation/devicetree/bindings/pinctrl/qcom,msm8976-pinctrl.txt

···
+Qualcomm MSM8976 TLMM block
+
+This binding describes the Top Level Mode Multiplexer block found in the
+MSM8956 and MSM8976 platforms.
+
+- compatible:
+	Usage: required
+	Value type: <string>
+	Definition: must be "qcom,msm8976-pinctrl"
+
+- reg:
+	Usage: required
+	Value type: <prop-encoded-array>
+	Definition: the base address and size of the TLMM register space.
+
+- interrupts:
+	Usage: required
+	Value type: <prop-encoded-array>
+	Definition: should specify the TLMM summary IRQ.
+
+- interrupt-controller:
+	Usage: required
+	Value type: <none>
+	Definition: identifies this node as an interrupt controller
+
+- #interrupt-cells:
+	Usage: required
+	Value type: <u32>
+	Definition: must be 2. Specifying the pin number and flags, as defined
+		    in <dt-bindings/interrupt-controller/irq.h>
+
+- gpio-controller:
+	Usage: required
+	Value type: <none>
+	Definition: identifies this node as a gpio controller
+
+- #gpio-cells:
+	Usage: required
+	Value type: <u32>
+	Definition: must be 2. Specifying the pin number and flags, as defined
+		    in <dt-bindings/gpio/gpio.h>
+
+- gpio-ranges:
+	Usage: required
+	Definition:  see ../gpio/gpio.txt
+
+- gpio-reserved-ranges:
+	Usage: optional
+	Definition: see ../gpio/gpio.txt
+
+Please refer to ../gpio/gpio.txt and ../interrupt-controller/interrupts.txt for
+a general description of GPIO and interrupt bindings.
+
+Please refer to pinctrl-bindings.txt in this directory for details of the
+common pinctrl bindings used by client devices, including the meaning of the
+phrase "pin configuration node".
+
+The pin configuration nodes act as a container for an arbitrary number of
+subnodes. Each of these subnodes represents some desired configuration for a
+pin, a group, or a list of pins or groups. This configuration can include the
+mux function to select on those pin(s)/group(s), and various pin configuration
+parameters, such as pull-up, drive strength, etc.
+
+
+PIN CONFIGURATION NODES:
+
+The name of each subnode is not important; all subnodes should be enumerated
+and processed purely based on their content.
+
+Each subnode only affects those parameters that are explicitly listed. In
+other words, a subnode that lists a mux function but no pin configuration
+parameters implies no information about any pin configuration parameters.
+Similarly, a pin subnode that describes a pullup parameter implies no
+information about e.g. the mux function.
+
+
+The following generic properties as defined in pinctrl-bindings.txt are valid
+to specify in a pin configuration subnode:
+
+- pins:
+	Usage: required
+	Value type: <string-array>
+	Definition: List of gpio pins affected by the properties specified in
+		    this subnode.
+
+		    Valid pins are:
+		      gpio0-gpio145
+		        Supports mux, bias and drive-strength
+
+		      sdc1_clk, sdc1_cmd, sdc1_data,
+		      sdc2_clk, sdc2_cmd, sdc2_data,
+		      sdc3_clk, sdc3_cmd, sdc3_data
+		        Supports bias and drive-strength
+
+- function:
+	Usage: required
+	Value type: <string>
+	Definition: Specify the alternative function to be configured for the
+		    specified pins. Functions are only valid for gpio pins.
+		    Valid values are:
+
+		    gpio, blsp_uart1, blsp_spi1, smb_int, blsp_i2c1, blsp_spi2,
+		    blsp_uart2, blsp_i2c2, gcc_gp1_clk_b, blsp_spi3,
+		    qdss_tracedata_b, blsp_i2c3, gcc_gp2_clk_b, gcc_gp3_clk_b,
+		    blsp_spi4, cap_int, blsp_i2c4, blsp_spi5, blsp_uart5,
+		    qdss_traceclk_a, m_voc, blsp_i2c5, qdss_tracectl_a,
+		    qdss_tracedata_a, blsp_spi6, blsp_uart6, qdss_tracectl_b,
+		    blsp_i2c6, qdss_traceclk_b, mdp_vsync, pri_mi2s_mclk_a,
+		    sec_mi2s_mclk_a, cam_mclk, cci0_i2c, cci1_i2c, blsp1_spi,
+		    blsp3_spi, gcc_gp1_clk_a, gcc_gp2_clk_a, gcc_gp3_clk_a,
+		    uim_batt, sd_write, uim1_data, uim1_clk, uim1_reset,
+		    uim1_present, uim2_data, uim2_clk, uim2_reset,
+		    uim2_present, ts_xvdd, mipi_dsi0, us_euro, ts_resout,
+		    ts_sample, sec_mi2s_mclk_b, pri_mi2s, codec_reset,
+		    cdc_pdm0, us_emitter, pri_mi2s_mclk_b, pri_mi2s_mclk_c,
+		    lpass_slimbus, lpass_slimbus0, lpass_slimbus1, codec_int1,
+		    codec_int2, wcss_bt, sdc3, wcss_wlan2, wcss_wlan1,
+		    wcss_wlan0, wcss_wlan, wcss_fm, key_volp, key_snapshot,
+		    key_focus, key_home, pwr_down, dmic0_clk, hdmi_int,
+		    dmic0_data, wsa_vi, wsa_en, blsp_spi8, wsa_irq, blsp_i2c8,
+		    pa_indicator, modem_tsync, ssbi_wtr1, gsm1_tx, gsm0_tx,
+		    sdcard_det, sec_mi2s, ss_switch,
+
+- bias-disable:
+	Usage: optional
+	Value type: <none>
+	Definition: The specified pins should be configured as no pull.
+
+- bias-pull-down:
+	Usage: optional
+	Value type: <none>
+	Definition: The specified pins should be configured as pull down.
+
+- bias-pull-up:
+	Usage: optional
+	Value type: <none>
+	Definition: The specified pins should be configured as pull up.
+
+- output-high:
+	Usage: optional
+	Value type: <none>
+	Definition: The specified pins are configured in output mode, driven
+		    high.
+		    Not valid for sdc pins.
+
+- output-low:
+	Usage: optional
+	Value type: <none>
+	Definition: The specified pins are configured in output mode, driven
+		    low.
+		    Not valid for sdc pins.
+
+- drive-strength:
+	Usage: optional
+	Value type: <u32>
+	Definition: Selects the drive strength for the specified pins, in mA.
+		    Valid values are: 2, 4, 6, 8, 10, 12, 14 and 16
+
+Example:
+
+	tlmm: pinctrl@1000000 {
+		compatible = "qcom,msm8976-pinctrl";
+		reg = <0x1000000 0x300000>;
+		interrupts = <GIC_SPI 208 IRQ_TYPE_LEVEL_HIGH>;
+		gpio-controller;
+		#gpio-cells = <2>;
+		gpio-ranges = <&tlmm 0 0 145>;
+		interrupt-controller;
+		#interrupt-cells = <2>;
+
+		blsp1_uart2_active: blsp1_uart2_active {
+			mux {
+				pins = "gpio4", "gpio5", "gpio6", "gpio7";
+				function = "blsp_uart2";
+			};
+
+			config {
+				pins = "gpio4", "gpio5", "gpio6", "gpio7";
+				drive-strength = <2>;
+				bias-disable;
+			};
+		};
+	};