[U-Boot] [PATCH V2 07/11] dm: adc: add Exynos54xx compatible ADC driver

Przemyslaw Marczak p.marczak at samsung.com
Mon Sep 21 14:26:39 CEST 2015 

This commit adds driver for Exynos54xx ADC subsystem.

The driver is implemented using driver model,
amd provides ADC uclass's operations:
- adc_init()
- adc_data()

This driver uses sdelay() function on pooling, so it can
be used before the delay timer is inited.
The basic parameters of ADC conversion, are:
- sample rate: 600KSPS
- output the data as average of 8 time conversion

ADC features:
- sample rate: 600KSPS
- resolution: 12-bit
- channels: 10 (analog multiplexer)

Signed-off-by: Przemyslaw Marczak <p.marczak at samsung.com>
---
Changes V2:
- new commit - move previous adc driver from SoC directory to drivers/adc
---
 arch/arm/mach-exynos/include/mach/adc.h |  45 ++++++++++++++
 drivers/adc/Kconfig                     |   9 +++
 drivers/adc/Makefile                    |   1 +
 drivers/adc/exynos-adc.c                | 102 ++++++++++++++++++++++++++++++++
 4 files changed, 157 insertions(+)
 create mode 100644 drivers/adc/exynos-adc.c

diff --git a/arch/arm/mach-exynos/include/mach/adc.h b/arch/arm/mach-exynos/include/mach/adc.h
index a0e26d7..228acf4 100644
--- a/arch/arm/mach-exynos/include/mach/adc.h
+++ b/arch/arm/mach-exynos/include/mach/adc.h
@@ -9,6 +9,38 @@
 #ifndef __ASM_ARM_ARCH_ADC_H_
 #define __ASM_ARM_ARCH_ADC_H_
 
+#define ADC_V2_CON1_SOFT_RESET		(0x2 << 1)
+#define ADC_V2_CON1_STC_EN		(0x1)
+
+#define ADC_V2_CON2_OSEL(x)		(((x) & 0x1) << 10)
+#define OSEL_2S				(0x0)
+#define OSEL_BINARY			(0x1)
+#define ADC_V2_CON2_ESEL(x)		(((x) & 0x1) << 9)
+#define ESEL_ADC_EVAL_TIME_40CLK	(0x0)
+#define ESEL_ADC_EVAL_TIME_20CLK	(0x1)
+#define ADC_V2_CON2_HIGHF(x)		(((x) & 0x1) << 8)
+#define HIGHF_CONV_RATE_30KSPS		(0x0)
+#define HIGHF_CONV_RATE_600KSPS		(0x1)
+#define ADC_V2_CON2_C_TIME(x)		(((x) & 0x7) << 4)
+#define ADC_V2_CON2_CHAN_SEL(x)		((x) & 0xf)
+
+#define ADC_V2_GET_STATUS_FLAG(x)	(((x) >> 2) & 0x1)
+#define FLAG_CONV_END			(0x1)
+
+#define ADC_V2_INT_DISABLE		(0x0)
+#define ADC_V2_INT_ENABLE		(0x1)
+#define INT_NOT_GENERATED		(0x0)
+#define INT_GENERATED			(0x1)
+
+#define ADC_V2_VERSION			(0x80000008)
+
+#define ADC_V2_MAX_CHANNEL		(9)
+
+/* For default 8 time convertion with sample rate 600 kSPS - 15us timeout */
+#define ADC_V2_CONV_TIMEOUT_US		(15)
+
+#define ADC_V2_DAT_MASK			(0xfff)
+
 #ifndef __ASSEMBLY__
 struct s5p_adc {
 	unsigned int adccon;
@@ -21,6 +53,19 @@ struct s5p_adc {
 	unsigned int adcmux;
 	unsigned int adcclrintpndnup;
 };
+
+struct exynos_adc_v2 {
+	unsigned int con1;
+	unsigned int con2;
+	unsigned int status;
+	unsigned int dat;
+	unsigned int int_en;
+	unsigned int int_status;
+	unsigned int reserved[2];
+	unsigned int version;
+};
+
+int exynos_adc_read_channel(int channel);
 #endif
 
 #endif /* __ASM_ARM_ARCH_ADC_H_ */
diff --git a/drivers/adc/Kconfig b/drivers/adc/Kconfig
index 1cb1a8d..8ee6531 100644
--- a/drivers/adc/Kconfig
+++ b/drivers/adc/Kconfig
@@ -6,3 +6,12 @@ config ADC
 	  - device enable
 	  - conversion init
 	  - conversion start and return data with data mask
+
+config ADC_EXYNOS
+	bool "Enable Exynos 54xx ADC driver"
+	help
+	  This enables basic driver for Exynos ADC compatible with Exynos54xx.
+	  It provides:
+	  - 10 analog input channels
+	  - 12-bit resolution
+	  - 600 KSPS of sample rate
diff --git a/drivers/adc/Makefile b/drivers/adc/Makefile
index c4d9618..eb85b8b 100644
--- a/drivers/adc/Makefile
+++ b/drivers/adc/Makefile
@@ -6,3 +6,4 @@
 #
 
 obj-$(CONFIG_ADC) += adc-uclass.o
+obj-$(CONFIG_ADC_EXYNOS) += exynos-adc.o
diff --git a/drivers/adc/exynos-adc.c b/drivers/adc/exynos-adc.c
new file mode 100644
index 0000000..fdffea0
--- /dev/null
+++ b/drivers/adc/exynos-adc.c
@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2015 Samsung Electronics
+ * Przemyslaw Marczak <p.marczak at samsung.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+#include <common.h>
+#include <errno.h>
+#include <dm.h>
+#include <adc.h>
+#include <asm/arch/adc.h>
+
+struct exynos_adc_priv {
+	struct exynos_adc_v2 *regs;
+};
+
+extern void sdelay(unsigned long loops);
+
+int exynos_adc_data(struct udevice *dev, unsigned int *data)
+{
+	struct exynos_adc_priv *priv = dev_get_priv(dev);
+	struct exynos_adc_v2 *regs = priv->regs;
+	unsigned int cfg, timeout_us = ADC_V2_CONV_TIMEOUT_US;
+
+	/* Start conversion */
+	cfg = readl(&regs->con1);
+	writel(cfg | ADC_V2_CON1_STC_EN, &regs->con1);
+
+	while (ADC_V2_GET_STATUS_FLAG(readl(&regs->status)) != FLAG_CONV_END) {
+		sdelay(4);
+		if (!timeout_us--) {
+			error("ADC conversion timeout!");
+			return -ETIME;
+		}
+	}
+
+	*data = readl(&regs->dat) & ADC_V2_DAT_MASK;
+
+	return 0;
+}
+
+int exynos_adc_init(struct udevice *dev, int channel)
+{
+	struct exynos_adc_priv *priv = dev_get_priv(dev);
+	struct exynos_adc_v2 *regs = priv->regs;
+	unsigned int cfg;
+
+	/* Check HW version */
+	if (readl(&regs->version) != ADC_V2_VERSION) {
+		error("This driver supports only ADC v2!");
+		return -ENXIO;
+	}
+
+	/* ADC Reset */
+	writel(ADC_V2_CON1_SOFT_RESET, &regs->con1);
+
+	/* Disable INT - will read status only */
+	writel(0x0, &regs->int_en);
+
+	/* CON2 - set conversion parameters */
+	cfg = ADC_V2_CON2_C_TIME(3); /* Conversion times: (1 << 3) = 8 */
+	cfg |= ADC_V2_CON2_OSEL(OSEL_BINARY);
+	cfg |= ADC_V2_CON2_CHAN_SEL(channel);
+	cfg |= ADC_V2_CON2_ESEL(ESEL_ADC_EVAL_TIME_20CLK);
+	cfg |= ADC_V2_CON2_HIGHF(HIGHF_CONV_RATE_600KSPS);
+	writel(cfg, &regs->con2);
+
+	return 0;
+}
+
+int exynos_adc_ofdata_to_platdata(struct udevice *dev)
+{
+	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
+	struct exynos_adc_priv *priv = dev_get_priv(dev);
+
+	priv->regs = (struct exynos_adc_v2 *)dev_get_addr(dev);
+
+	uc_pdata->data_mask = ADC_V2_DAT_MASK;
+	/* Channel count starts from 0 */
+	uc_pdata->channels_num = ADC_V2_MAX_CHANNEL + 1;
+
+	return 0;
+}
+
+static const struct adc_ops exynos_adc_ops = {
+	.adc_init = exynos_adc_init,
+	.adc_data = exynos_adc_data,
+};
+
+static const struct udevice_id exynos_adc_ids[] = {
+	{ .compatible = "samsung,exynos-adc-v2" },
+	{ }
+};
+
+U_BOOT_DRIVER(exynos_adc) = {
+	.name		= "exynos-adc",
+	.id		= UCLASS_ADC,
+	.of_match	= exynos_adc_ids,
+	.ops		= &exynos_adc_ops,
+	.ofdata_to_platdata = exynos_adc_ofdata_to_platdata,
+	.priv_auto_alloc_size = sizeof(struct exynos_adc_priv),
+};
-- 
1.9.1

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