[U-Boot] [PATCH V3 08/14] dm: adc: add Exynos54xx compatible ADC driver

Przemyslaw Marczak p.marczak at samsung.com
Tue Oct 27 13:08:01 CET 2015 

This commit adds driver for Exynos54xx ADC subsystem.

The driver is implemented using driver model, amd provides
ADC uclass's methods for ADC single channel operations:
- adc_start_channel()
- adc_channel_data()
- adc_stop()

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>
Cc: Minkyu Kang <mk7.kang at samsung.com>
Cc: Simon Glass <sjg at chromium.org>
---
Changes V2:
- new commit - move previous adc driver from SoC directory to drivers/adc
Changes V3:
- rework the driver to fit new API
- remove call to sdelay() from driver's code
- add active_channel to keep consistency between ADC request and result
---
 arch/arm/mach-exynos/include/mach/adc.h |  44 ++++++++++
 drivers/adc/Kconfig                     |   9 ++
 drivers/adc/Makefile                    |   1 +
 drivers/adc/exynos-adc.c                | 145 ++++++++++++++++++++++++++++++++
 4 files changed, 199 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..9af51ab 100644
--- a/arch/arm/mach-exynos/include/mach/adc.h
+++ b/arch/arm/mach-exynos/include/mach/adc.h
@@ -9,6 +9,39 @@
 #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_MASK	0xf
+#define ADC_V2_CON2_CHAN_SEL(x)		((x) & ADC_V2_CON2_CHAN_SEL_MASK)
+
+#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 +54,17 @@ 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;
+};
 #endif
 
 #endif /* __ASM_ARM_ARCH_ADC_H_ */
diff --git a/drivers/adc/Kconfig b/drivers/adc/Kconfig
index b6e226a..223b65e 100644
--- a/drivers/adc/Kconfig
+++ b/drivers/adc/Kconfig
@@ -10,3 +10,12 @@ config ADC
 	  - methods for get Vdd/Vss reference Voltage values with polarity
 	  - support supply's phandle with auto-enable
 	  - supply polarity setting in fdt
+
+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..534e68d
--- /dev/null
+++ b/drivers/adc/exynos-adc.c
@@ -0,0 +1,145 @@
+/*
+ * 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 {
+	int active_channel;
+	struct exynos_adc_v2 *regs;
+};
+
+int exynos_adc_channel_data(struct udevice *dev, int channel,
+			    unsigned int *data)
+{
+	struct exynos_adc_priv *priv = dev_get_priv(dev);
+	struct exynos_adc_v2 *regs = priv->regs;
+
+	if (channel != priv->active_channel) {
+		error("Requested channel is not active!");
+		return -EINVAL;
+	}
+
+	if (ADC_V2_GET_STATUS_FLAG(readl(&regs->status)) != FLAG_CONV_END)
+		return -EBUSY;
+
+	*data = readl(&regs->dat) & ADC_V2_DAT_MASK;
+
+	return 0;
+}
+
+int exynos_adc_start_channel(struct udevice *dev, int channel)
+{
+	struct exynos_adc_priv *priv = dev_get_priv(dev);
+	struct exynos_adc_v2 *regs = priv->regs;
+	unsigned int cfg;
+
+	/* Choose channel */
+	cfg = readl(&regs->con2);
+	cfg &= ~ADC_V2_CON2_CHAN_SEL_MASK;
+	cfg |= ADC_V2_CON2_CHAN_SEL(channel);
+	writel(cfg, &regs->con2);
+
+	/* Start conversion */
+	cfg = readl(&regs->con1);
+	writel(cfg | ADC_V2_CON1_STC_EN, &regs->con1);
+
+	priv->active_channel = channel;
+
+	return 0;
+}
+
+int exynos_adc_stop(struct udevice *dev)
+{
+	struct exynos_adc_priv *priv = dev_get_priv(dev);
+	struct exynos_adc_v2 *regs = priv->regs;
+	unsigned int cfg;
+
+	/* Stop conversion */
+	cfg = readl(&regs->con1);
+	cfg |= ~ADC_V2_CON1_STC_EN;
+
+	writel(cfg, &regs->con1);
+
+	priv->active_channel = -1;
+
+	return 0;
+}
+
+int exynos_adc_probe(struct udevice *dev)
+{
+	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_ESEL(ESEL_ADC_EVAL_TIME_20CLK);
+	cfg |= ADC_V2_CON2_HIGHF(HIGHF_CONV_RATE_600KSPS);
+	writel(cfg, &regs->con2);
+
+	priv->active_channel = -1;
+
+	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);
+	if (priv->regs == (struct exynos_adc_v2 *)FDT_ADDR_T_NONE) {
+		error("Dev: %s - can't get address!", dev->name);
+		return -ENODATA;
+	}
+
+	uc_pdata->data_mask = ADC_V2_DAT_MASK;
+	uc_pdata->data_format = ADC_DATA_FORMAT_BIN;
+	uc_pdata->data_timeout_us = ADC_V2_CONV_TIMEOUT_US;
+
+	/* Mask available channel bits: [0:9] */
+	uc_pdata->channel_mask = (2 << ADC_V2_MAX_CHANNEL) - 1;
+
+	return 0;
+}
+
+static const struct adc_ops exynos_adc_ops = {
+	.start_channel = exynos_adc_start_channel,
+	.channel_data = exynos_adc_channel_data,
+	.stop = exynos_adc_stop,
+};
+
+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,
+	.probe		= exynos_adc_probe,
+	.ofdata_to_platdata = exynos_adc_ofdata_to_platdata,
+	.priv_auto_alloc_size = sizeof(struct exynos_adc_priv),
+};
-- 
1.9.1

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