input: add spl adc key driver

Providing a mininum adc key driver for SPL, which does not
depend on key uclass, but ADC uclass is still required.

Signed-off-by: Joseph Chen <chenjh@rock-chips.com>
Change-Id: I80f861780acd9c47d345b95762a4dd39d19ea6fc

drivers/input/Kconfig

@@ -105,6 +105,12 @@ config ADC_KEY
 	help
 	  This adds a driver for the adc keys support.
 
+config SPL_ADC_KEY
+        bool "Enable SPL adc keys support without DM"
+        depends on SPL_INPUT
+        help
+          This adds a driver for the SPL adc keys support
+
 config GPIO_KEY
 	bool "Enable gpio keys support"
 	depends on DM_KEY

drivers/input/Makefile

@@ -28,4 +28,7 @@ ifdef CONFIG_PS2KBD
 obj-y += keyboard.o pc_keyb.o
 obj-$(CONFIG_PS2MULT) += ps2mult.o ps2ser.o
 endif
+
+else
+obj-$(CONFIG_SPL_ADC_KEY) += spl_adc_key.o
 endif

drivers/input/spl_adc_key.c

@@ -0,0 +1,73 @@
+/*
+ * (C) Copyright 2020 Rockchip Electronics Co., Ltd
+ *
+ * SPDX-License-Identifier:     GPL-2.0+
+ */
+
+#include <common.h>
+#include <adc.h>
+#include <fdtdec.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+int key_read(int code)
+{
+	const void *fdt_blob = gd->fdt_blob;
+	int adc_node, offset;
+	int cd, channel, adc;
+	int ret, vref, mv;
+	int min, max;
+	int margin = 30;
+	uint val;
+	u32 chn[2];
+
+	adc_node = fdt_node_offset_by_compatible(fdt_blob, 0, "adc-keys");
+	if (adc_node < 0) {
+		debug("No 'adc-keys' node, ret=%d\n", adc_node);
+		return 0;
+	}
+
+	ret = fdtdec_get_int_array(fdt_blob, adc_node, "io-channels",
+				   chn, ARRAY_SIZE(chn));
+	if (ret) {
+		debug("Can't read 'io-channels', ret=%d\n", ret);
+		return 0;
+	}
+
+	vref = fdtdec_get_int(fdt_blob, adc_node,
+			      "keyup-threshold-microvolt", -1);
+	if (vref < 0) {
+		debug("Can't read 'keyup-threshold-microvolt'\n");
+		return 0;
+	}
+
+	channel = chn[1];
+
+	for (offset = fdt_first_subnode(fdt_blob, adc_node);
+	     offset >= 0;
+	     offset = fdt_next_subnode(fdt_blob, offset)) {
+		cd = fdtdec_get_int(fdt_blob, offset, "linux,code", -1);
+		if (cd == code) {
+			mv = fdtdec_get_int(fdt_blob, offset,
+					    "press-threshold-microvolt", -1);
+			if (mv < 0) {
+				debug("Can't read 'press-threshold-microvolt'\n");
+				return 0;
+			}
+
+			adc = mv / (vref / 1024); /* 10-bit adc */
+			max = adc + margin;
+			min = adc > margin ? adc - margin : 0;
+			ret = adc_channel_single_shot("saradc", channel, &val);
+			if (ret) {
+				debug("Failed to read adc%d, ret=%d\n",
+				      channel, ret);
+				return 0;
+			}
+
+			return (val >= min && val <= max);
+		}
+	}
+
+	return 0;
+}