Re: [PATCH v2 2/6] mfd: stm32-adc: Add support for stm32 ADC

From: Fabrice Gasnier
Date: Tue Nov 15 2016 - 05:49:00 EST

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In reply to: Lee Jones: "Re: [PATCH v2 2/6] mfd: stm32-adc: Add support for stm32 ADC"
Next in thread: Jonathan Cameron: "Re: [PATCH v2 2/6] mfd: stm32-adc: Add support for stm32 ADC"
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On 11/14/2016 05:47 PM, Lee Jones wrote:

On Sat, 12 Nov 2016, Jonathan Cameron wrote:

On 10/11/16 16:18, Fabrice Gasnier wrote:

Add core driver for STMicroelectronics STM32 ADC (Analog to Digital
Converter). STM32 ADC can be composed of up to 3 ADCs with shared
resources like clock prescaler, common interrupt line and analog
reference voltage.
This core driver basically manages shared resources.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>

Looks good to me (other than the build issue obviously ;)

Hi Jonathan,
Thanks for your review.
I'll fix build issue, sure ;-)

The fun bit will be trying to keep the whole thing this clean as you
add the more 'interesting' functionality. *fingers crossed*

Yes... But in the end, splitting shared resources in core driver makes it more simple.
Not sure there will be more complexity here.

Acked-by: Jonathan Cameron <jic23@xxxxxxxxxx>

There isn't anything MFD about this driver.

Please move it into IIO.

Hmm, there is no other sub sysbtem that may be used here, ADC driver belongs to IIO.
Also, of_platform_populate() is being used here. This can perfectly be called from within IIO.

Jonathan, can this "stm32-adc-core" driver be moved to, and live in drivers/iio/adc ?
(e.g. in addition to stm32-adc iio driver)
Is it ok for you ?

Please advise,
Best Regards,
Fabrice

---
drivers/mfd/Kconfig | 14 ++
drivers/mfd/Makefile | 1 +
drivers/mfd/stm32-adc-core.c | 301 +++++++++++++++++++++++++++++++++++++
include/linux/mfd/stm32-adc-core.h | 52 +++++++
4 files changed, 368 insertions(+)
create mode 100644 drivers/mfd/stm32-adc-core.c
create mode 100644 include/linux/mfd/stm32-adc-core.h

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index c6df644..2580cee 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1152,6 +1152,20 @@ config MFD_PALMAS
If you say yes here you get support for the Palmas
series of PMIC chips from Texas Instruments.
+config MFD_STM32_ADC
+ tristate "STMicroelectronics STM32 adc"
+ depends on ARCH_STM32 || COMPILE_TEST
+ depends on OF
+ select MFD_CORE
+ select REGULATOR
+ select REGULATOR_FIXED_VOLTAGE
+ help
+ Select this option to enable the core driver for STMicroelectronics
+ STM32 analog-to-digital converter (ADC).
+
+ This driver can also be built as a module. If so, the module
+ will be called stm32-adc-core.
+
config TPS6105X
tristate "TI TPS61050/61052 Boost Converters"
depends on I2C
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 9834e66..4571506 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -185,6 +185,7 @@ obj-$(CONFIG_MFD_INTEL_LPSS_PCI) += intel-lpss-pci.o
obj-$(CONFIG_MFD_INTEL_LPSS_ACPI) += intel-lpss-acpi.o
obj-$(CONFIG_MFD_INTEL_MSIC) += intel_msic.o
obj-$(CONFIG_MFD_PALMAS) += palmas.o
+obj-$(CONFIG_MFD_STM32_ADC) += stm32-adc-core.o
obj-$(CONFIG_MFD_VIPERBOARD) += viperboard.o
obj-$(CONFIG_MFD_RC5T583) += rc5t583.o rc5t583-irq.o
obj-$(CONFIG_MFD_RK808) += rk808.o
diff --git a/drivers/mfd/stm32-adc-core.c b/drivers/mfd/stm32-adc-core.c
new file mode 100644
index 0000000..bcf52fb
--- /dev/null
+++ b/drivers/mfd/stm32-adc-core.c
@@ -0,0 +1,301 @@
+/*
+ * This file is part of STM32 ADC driver
+ *
+ * Copyright (C) 2016, STMicroelectronics - All Rights Reserved
+ * Author: Fabrice Gasnier <fabrice.gasnier@xxxxxx>.
+ *
+ * Inspired from: fsl-imx25-tsadc
+ *
+ * License type: GPLv2
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdesc.h>
+#include <linux/irqdomain.h>
+#include <linux/mfd/stm32-adc-core.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+/* STM32F4 - common registers for all ADC instances: 1, 2 & 3 */
+#define STM32F4_ADC_CSR (STM32_ADCX_COMN_OFFSET + 0x00)
+#define STM32F4_ADC_CCR (STM32_ADCX_COMN_OFFSET + 0x04)
+
+/* STM32F4_ADC_CSR - bit fields */
+#define STM32F4_EOC3 BIT(17)
+#define STM32F4_EOC2 BIT(9)
+#define STM32F4_EOC1 BIT(1)
+
+/* STM32F4_ADC_CCR - bit fields */
+#define STM32F4_ADC_ADCPRE_SHIFT 16
+#define STM32F4_ADC_ADCPRE_MASK GENMASK(17, 16)
+
+/* STM32 F4 maximum analog clock rate (from datasheet) */
+#define STM32F4_ADC_MAX_CLK_RATE 36000000
+
+/**
+ * struct stm32_adc_priv - stm32 ADC core private data
+ * @irq: irq for ADC block
+ * @domain: irq domain reference
+ * @aclk: clock reference for the analog circuitry
+ * @vref: regulator reference
+ * @common: common data for all ADC instances
+ */
+struct stm32_adc_priv {
+ int irq;
+ struct irq_domain *domain;
+ struct clk *aclk;
+ struct regulator *vref;
+ struct stm32_adc_common common;
+};
+
+static struct stm32_adc_priv *to_stm32_adc_priv(struct stm32_adc_common *com)
+{
+ return container_of(com, struct stm32_adc_priv, common);
+}
+
+/* STM32F4 ADC internal common clock prescaler division ratios */
+static int stm32f4_pclk_div[] = {2, 4, 6, 8};
+
+/**
+ * stm32f4_adc_clk_sel() - Select stm32f4 ADC common clock prescaler
+ * @priv: stm32 ADC core private data
+ * Select clock prescaler used for analog conversions, before using ADC.
+ */
+static int stm32f4_adc_clk_sel(struct platform_device *pdev,
+ struct stm32_adc_priv *priv)
+{
+ unsigned long rate;
+ u32 val;
+ int i;
+
+ rate = clk_get_rate(priv->aclk);
+ for (i = 0; i < ARRAY_SIZE(stm32f4_pclk_div); i++) {
+ if ((rate / stm32f4_pclk_div[i]) <= STM32F4_ADC_MAX_CLK_RATE)
+ break;
+ }
+ if (i >= ARRAY_SIZE(stm32f4_pclk_div))
+ return -EINVAL;
+
+ val = readl_relaxed(priv->common.base + STM32F4_ADC_CCR);
+ val &= ~STM32F4_ADC_ADCPRE_MASK;
+ val |= i << STM32F4_ADC_ADCPRE_SHIFT;
+ writel_relaxed(val, priv->common.base + STM32F4_ADC_CCR);
+
+ dev_dbg(&pdev->dev, "Using analog clock source at %ld kHz\n",
+ rate / (stm32f4_pclk_div[i] * 1000));
+
+ return 0;
+}
+
+/* ADC common interrupt for all instances */
+static void stm32_adc_irq_handler(struct irq_desc *desc)
+{
+ struct stm32_adc_priv *priv = irq_desc_get_handler_data(desc);
+ struct irq_chip *chip = irq_desc_get_chip(desc);
+ u32 status;
+
+ chained_irq_enter(chip, desc);
+ status = readl_relaxed(priv->common.base + STM32F4_ADC_CSR);
+
+ if (status & STM32F4_EOC1)
+ generic_handle_irq(irq_find_mapping(priv->domain, 0));
+
+ if (status & STM32F4_EOC2)
+ generic_handle_irq(irq_find_mapping(priv->domain, 1));
+
+ if (status & STM32F4_EOC3)
+ generic_handle_irq(irq_find_mapping(priv->domain, 2));
+
+ chained_irq_exit(chip, desc);
+};
+
+static int stm32_adc_domain_map(struct irq_domain *d, unsigned int irq,
+ irq_hw_number_t hwirq)
+{
+ irq_set_chip_data(irq, d->host_data);
+ irq_set_chip_and_handler(irq, &dummy_irq_chip, handle_level_irq);
+
+ return 0;
+}
+
+static void stm32_adc_domain_unmap(struct irq_domain *d, unsigned int irq)
+{
+ irq_set_chip_and_handler(irq, NULL, NULL);
+ irq_set_chip_data(irq, NULL);
+}
+
+static const struct irq_domain_ops stm32_adc_domain_ops = {
+ .map = stm32_adc_domain_map,
+ .unmap = stm32_adc_domain_unmap,
+ .xlate = irq_domain_xlate_onecell,
+};
+
+static int stm32_adc_irq_probe(struct platform_device *pdev,
+ struct stm32_adc_priv *priv)
+{
+ struct device_node *np = pdev->dev.of_node;
+
+ priv->irq = platform_get_irq(pdev, 0);
+ if (priv->irq < 0) {
+ dev_err(&pdev->dev, "failed to get irq\n");
+ return priv->irq;
+ }
+
+ priv->domain = irq_domain_add_simple(np, STM32_ADC_MAX_ADCS, 0,
+ &stm32_adc_domain_ops,
+ priv);
+ if (!priv->domain) {
+ dev_err(&pdev->dev, "Failed to add irq domain\n");
+ return -ENOMEM;
+ }
+
+ irq_set_chained_handler(priv->irq, stm32_adc_irq_handler);
+ irq_set_handler_data(priv->irq, priv);
+
+ return 0;
+}
+
+static void stm32_adc_irq_remove(struct platform_device *pdev,
+ struct stm32_adc_priv *priv)
+{
+ int hwirq;
+
+ for (hwirq = 0; hwirq < STM32_ADC_MAX_ADCS; hwirq++)
+ irq_dispose_mapping(irq_find_mapping(priv->domain, hwirq));
+ irq_domain_remove(priv->domain);
+ irq_set_chained_handler(priv->irq, NULL);
+}
+
+static int stm32_adc_probe(struct platform_device *pdev)
+{
+ struct stm32_adc_priv *priv;
+ struct device_node *np = pdev->dev.of_node;
+ struct resource *res;
+ int ret;
+
+ if (!pdev->dev.of_node)
+ return -ENODEV;
+
+ priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ priv->common.base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(priv->common.base))
+ return PTR_ERR(priv->common.base);
+
+ priv->vref = devm_regulator_get(&pdev->dev, "vref");
+ if (IS_ERR(priv->vref)) {
+ ret = PTR_ERR(priv->vref);
+ dev_err(&pdev->dev, "vref get failed, %d\n", ret);
+ return ret;
+ }
+
+ ret = regulator_enable(priv->vref);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "vref enable failed\n");
+ return ret;
+ }
+
+ ret = regulator_get_voltage(priv->vref);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "vref get voltage failed, %d\n", ret);
+ goto err_regulator_disable;
+ }
+ priv->common.vref_mv = ret / 1000;
+ dev_dbg(&pdev->dev, "vref+=%dmV\n", priv->common.vref_mv);
+
+ priv->aclk = devm_clk_get(&pdev->dev, "adc");
+ if (IS_ERR(priv->aclk)) {
+ ret = PTR_ERR(priv->aclk);
+ dev_err(&pdev->dev, "Can't get 'adc' clock\n");
+ goto err_regulator_disable;
+ }
+
+ ret = clk_prepare_enable(priv->aclk);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "adc clk enable failed\n");
+ goto err_regulator_disable;
+ }
+
+ ret = stm32f4_adc_clk_sel(pdev, priv);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "adc clk selection failed\n");
+ goto err_clk_disable;
+ }
+
+ ret = stm32_adc_irq_probe(pdev, priv);
+ if (ret < 0)
+ goto err_clk_disable;
+
+ platform_set_drvdata(pdev, &priv->common);
+
+ ret = of_platform_populate(np, NULL, NULL, &pdev->dev);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to populate DT children\n");
+ goto err_irq_remove;
+ }
+
+ return 0;
+
+err_irq_remove:
+ stm32_adc_irq_remove(pdev, priv);
+
+err_clk_disable:
+ clk_disable_unprepare(priv->aclk);
+
+err_regulator_disable:
+ regulator_disable(priv->vref);
+
+ return ret;
+}
+
+static int stm32_adc_remove(struct platform_device *pdev)
+{
+ struct stm32_adc_common *common = platform_get_drvdata(pdev);
+ struct stm32_adc_priv *priv = to_stm32_adc_priv(common);
+
+ of_platform_depopulate(&pdev->dev);
+ stm32_adc_irq_remove(pdev, priv);
+ clk_disable_unprepare(priv->aclk);
+ regulator_disable(priv->vref);
+
+ return 0;
+}
+
+static const struct of_device_id stm32_adc_of_match[] = {
+ { .compatible = "st,stm32f4-adc-core" },
+};
+MODULE_DEVICE_TABLE(of, stm32_adc_of_match);
+
+static struct platform_driver stm32_adc_driver = {
+ .probe = stm32_adc_probe,
+ .remove = stm32_adc_remove,
+ .driver = {
+ .name = "stm32-adc-core",
+ .of_match_table = stm32_adc_of_match,
+ },
+};
+module_platform_driver(stm32_adc_driver);
+
+MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@xxxxxx>");
+MODULE_DESCRIPTION("STMicroelectronics STM32 ADC MFD driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:stm32-adc-core");
diff --git a/include/linux/mfd/stm32-adc-core.h b/include/linux/mfd/stm32-adc-core.h
new file mode 100644
index 0000000..081fa5f
--- /dev/null
+++ b/include/linux/mfd/stm32-adc-core.h
@@ -0,0 +1,52 @@
+/*
+ * This file is part of STM32 ADC driver
+ *
+ * Copyright (C) 2016, STMicroelectronics - All Rights Reserved
+ * Author: Fabrice Gasnier <fabrice.gasnier@xxxxxx>.
+ *
+ * License type: GPLv2
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __STM32_ADC_H
+#define __STM32_ADC_H
+
+/*
+ * STM32 - ADC global register map
+ * ________________________________________________________
+ * | Offset | Register |
+ * --------------------------------------------------------
+ * | 0x000 | Master ADC1 |
+ * --------------------------------------------------------
+ * | 0x100 | Slave ADC2 |
+ * --------------------------------------------------------
+ * | 0x200 | Slave ADC3 |
+ * --------------------------------------------------------
+ * | 0x300 | Master & Slave common regs |
+ * --------------------------------------------------------
+ */
+#define STM32_ADC_MAX_ADCS 3
+#define STM32_ADCX_COMN_OFFSET 0x300
+
+/**
+ * struct stm32_adc_common - stm32 ADC driver common data (for all instances)
+ * @base: control registers base cpu addr
+ * @vref_mv: vref voltage (mv)
+ */
+struct stm32_adc_common {
+ void __iomem *base;
+ int vref_mv;
+};
+
+#endif

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In reply to: Lee Jones: "Re: [PATCH v2 2/6] mfd: stm32-adc: Add support for stm32 ADC"
Next in thread: Jonathan Cameron: "Re: [PATCH v2 2/6] mfd: stm32-adc: Add support for stm32 ADC"
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