[PATCH v5 2/2] iio: adc: Add the NXP SAR ADC support for the s32g2/3 platforms

Daniel Lezcano
2025-10-17T16:42:51Z

From: Stefan-Gabriel Mirea <stefan-gabriel.mirea@nxp.com>

The NXP S32G2 and S32G3 platforms integrate a successive approximation
register (SAR) ADC. Two instances are available, each providing 8
multiplexed input channels with 12-bit resolution. The conversion rate
is up to 1 Msps depending on the configuration and sampling window.

The SAR ADC supports raw, buffer, and trigger modes. It can operate
in both single-shot and continuous conversion modes, with optional
hardware triggering through the cross-trigger unit (CTU) or external
events. An internal prescaler allows adjusting the sampling clock,
while per-channel programmable sampling times provide fine-grained
trade-offs between accuracy and latency. Automatic calibration is
performed at probe time to minimize offset and gain errors.

The driver is derived from the BSP implementation and has been partly
rewritten to comply with upstream requirements. For this reason, all
contributors are listed as co-developers, while the author refers to
the initial BSP driver file creator.

All modes have been validated on the S32G274-RDB2 platform using an
externally generated square wave captured by the ADC. Tests covered
buffered streaming via IIO, trigger synchronization, and accuracy
verification against a precision laboratory signal source.

Co-developed-by: Alexandru-Catalin Ionita <alexandru-catalin.ionita@nxp.com>
Signed-off-by: Alexandru-Catalin Ionita <alexandru-catalin.ionita@nxp.com>
Co-developed-by: Ciprian Costea <ciprianmarian.costea@nxp.com>
Signed-off-by: Ciprian Costea <ciprianmarian.costea@nxp.com>
Co-developed-by: Radu Pirea (NXP OSS) <radu-nicolae.pirea@oss.nxp.com>
Signed-off-by: Radu Pirea (NXP OSS) <radu-nicolae.pirea@oss.nxp.com>
Signed-off-by: Stefan-Gabriel Mirea <stefan-gabriel.mirea@nxp.com>
Co-developed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
drivers/iio/adc/Kconfig | 12 +
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/nxp-sar-adc.c | 1006 +++++++++++++++++++++++++++++++++
3 files changed, 1019 insertions(+)
create mode 100644 drivers/iio/adc/nxp-sar-adc.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 58a14e6833f6..363eb8a3a6f2 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1212,6 +1212,18 @@ config NPCM_ADC
This driver can also be built as a module. If so, the module
will be called npcm_adc.

+config NXP_SAR_ADC
+ tristate "NXP S32G SAR-ADC driver"
+ depends on ARCH_S32 || COMPILE_TEST
+ select IIO_BUFFER
+ select IIO_TRIGGERED_BUFFER
+ help
+ Say yes here to build support for S32G platforms
+ analog-to-digital converter.
+
+ This driver can also be built as a module. If so, the module will be
+ called nxp_sar_adc.
+
config PAC1921
tristate "Microchip Technology PAC1921 driver"
depends on I2C
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index d008f78dc010..c9d5bc976fd3 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -107,6 +107,7 @@ obj-$(CONFIG_MXS_LRADC_ADC) += mxs-lradc-adc.o
obj-$(CONFIG_NAU7802) += nau7802.o
obj-$(CONFIG_NCT7201) += nct7201.o
obj-$(CONFIG_NPCM_ADC) += npcm_adc.o
+obj-$(CONFIG_NXP_SAR_ADC) += nxp-sar-adc.o
obj-$(CONFIG_PAC1921) += pac1921.o
obj-$(CONFIG_PAC1934) += pac1934.o
obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
diff --git a/drivers/iio/adc/nxp-sar-adc.c b/drivers/iio/adc/nxp-sar-adc.c
new file mode 100644
index 000000000000..fa390c9d911f
--- /dev/null
+++ b/drivers/iio/adc/nxp-sar-adc.c
@@ -0,0 +1,1006 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * NXP SAR-ADC driver (adapted from Freescale Vybrid vf610 ADC driver
+ * by Fugang Duan <B38611@freescale.com>)
+ *
+ * Copyright 2013 Freescale Semiconductor, Inc.
+ * Copyright 2017, 2020-2025 NXP
+ * Copyright 2025, Linaro Ltd
+ */
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/circ_buf.h>
+#include <linux/cleanup.h>
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/iopoll.h>
+#include <linux/math64.h>
+#include <linux/minmax.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/time.h>
+#include <linux/types.h>
+#include <linux/units.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
+
+/* SAR ADC registers. */
+#define NXP_SAR_ADC_CDR(__base, __channel) (((__base) + 0x100) + ((__channel) * 0x4))
+
+#define NXP_SAR_ADC_CDR_CDATA_MASK GENMASK(11, 0)
+#define NXP_SAR_ADC_CDR_VALID BIT(19)
+
+/* Main Configuration Register */
+#define NXP_SAR_ADC_MCR(__base) ((__base) + 0x00)
+
+#define NXP_SAR_ADC_MCR_PWDN BIT(0)
+#define NXP_SAR_ADC_MCR_ACKO BIT(5)
+#define NXP_SAR_ADC_MCR_ADCLKSEL BIT(8)
+#define NXP_SAR_ADC_MCR_TSAMP_MASK GENMASK(10, 9)
+#define NXP_SAR_ADC_MCR_NRSMPL_MASK GENMASK(12, 11)
+#define NXP_SAR_ADC_MCR_AVGEN BIT(13)
+#define NXP_SAR_ADC_MCR_CALSTART BIT(14)
+#define NXP_SAR_ADC_MCR_NSTART BIT(24)
+#define NXP_SAR_ADC_MCR_MODE BIT(29)
+#define NXP_SAR_ADC_MCR_OWREN BIT(31)
+
+/* Main Status Register */
+#define NXP_SAR_ADC_MSR(__base) ((__base) + 0x04)
+
+#define NXP_SAR_ADC_MSR_CALBUSY BIT(29)
+#define NXP_SAR_ADC_MSR_CALFAIL BIT(30)
+
+/* Interrupt Status Register */
+#define NXP_SAR_ADC_ISR(__base) ((__base) + 0x10)
+
+#define NXP_SAR_ADC_ISR_ECH BIT(0)
+
+/* Channel Pending Register */
+#define NXP_SAR_ADC_CEOCFR0(__base) ((__base) + 0x14)
+#define NXP_SAR_ADC_CEOCFR1(__base) ((__base) + 0x18)
+
+#define NXP_SAR_ADC_EOC_CH(c) BIT((c) % 32)
+
+/* Interrupt Mask Register */
+#define NXP_SAR_ADC_IMR(__base) ((__base) + 0x20)
+
+/* Channel Interrupt Mask Register */
+#define NXP_SAR_ADC_CIMR0(__base) ((__base) + 0x24)
+#define NXP_SAR_ADC_CIMR1(__base) ((__base) + 0x28)
+
+/* DMA Setting Register */
+#define NXP_SAR_ADC_DMAE(__base) ((__base) + 0x40)
+
+#define NXP_SAR_ADC_DMAE_DMAEN BIT(0)
+#define NXP_SAR_ADC_DMAE_DCLR BIT(1)
+
+/* DMA Control register */
+#define NXP_SAR_ADC_DMAR0(__base) ((__base) + 0x44)
+#define NXP_SAR_ADC_DMAR1(__base) ((__base) + 0x48)
+
+/* Conversion Timing Register */
+#define NXP_SAR_ADC_CTR0(__base) ((__base) + 0x94)
+#define NXP_SAR_ADC_CTR1(__base) ((__base) + 0x98)
+
+#define NXP_SAR_ADC_CTR_INPSAMP_MIN 0x08
+#define NXP_SAR_ADC_CTR_INPSAMP_MAX 0xFF
+
+/* Normal Conversion Mask Register */
+#define NXP_SAR_ADC_NCMR0(__base) ((__base) + 0xa4)
+#define NXP_SAR_ADC_NCMR1(__base) ((__base) + 0xa8)
+
+/* Normal Conversion Mask Register field define */
+#define NXP_SAR_ADC_CH_MASK GENMASK(7, 0)
+
+/* Other field define */
+#define NXP_SAR_ADC_CONV_TIMEOUT_MS 100
+#define NXP_SAR_ADC_CONV_TIMEOUT_JF (msecs_to_jiffies(NXP_SAR_ADC_CONV_TIMEOUT_MS))
+#define NXP_SAR_ADC_CAL_TIMEOUT_US (100 * USEC_PER_MSEC)
+#define NXP_SAR_ADC_WAIT_US (2 * USEC_PER_MSEC)
+#define NXP_SAR_ADC_RESOLUTION 12
+
+/* Duration of conversion phases */
+#define NXP_SAR_ADC_TPT 2
+#define NXP_SAR_ADC_DP 2
+#define NXP_SAR_ADC_CT ((NXP_SAR_ADC_RESOLUTION + 2) * 4)
+#define NXP_SAR_ADC_CONV_TIME (NXP_SAR_ADC_TPT + NXP_SAR_ADC_CT + NXP_SAR_ADC_DP)
+
+#define NXP_SAR_ADC_NR_CHANNELS 8
+
+#define NXP_SAR_ADC_IIO_BUFF_SZ (NXP_SAR_ADC_NR_CHANNELS + (sizeof(u64) / sizeof(u16)))
+
+#define NXP_PAGE_SIZE SZ_4K
+#define NXP_SAR_ADC_DMA_SAMPLE_SZ DMA_SLAVE_BUSWIDTH_4_BYTES
+#define NXP_SAR_ADC_DMA_BUFF_SZ (NXP_PAGE_SIZE * NXP_SAR_ADC_DMA_SAMPLE_SZ)
+#define NXP_SAR_ADC_DMA_SAMPLE_CNT (NXP_SAR_ADC_DMA_BUFF_SZ / NXP_SAR_ADC_DMA_SAMPLE_SZ)
+
+struct nxp_sar_adc {
+ void __iomem *regs;
+ phys_addr_t regs_phys;
+ u8 current_channel;
+ u8 channels_used;
+ u16 value;
+ u32 vref_mV;
+
+ /* Save and restore context. */
+ u32 inpsamp;
+ u32 pwdn;
+
+ struct clk *clk;
+ struct dma_chan *dma_chan;
+ struct completion completion;
+ struct circ_buf dma_buf;
+
+ dma_addr_t rx_dma_buf;
+ dma_cookie_t cookie;
+
+ /* Protect circular buffers access. */
+ spinlock_t lock;
+
+ /* Array of enabled channels. */
+ u16 buffered_chan[NXP_SAR_ADC_NR_CHANNELS];
+
+ /* Buffer to be filled by the DMA. */
+ IIO_DECLARE_BUFFER_WITH_TS(u16, buffer, NXP_SAR_ADC_NR_CHANNELS);
+};
+
+struct nxp_sar_adc_data {
+ u32 vref_mV;
+ const char *model;
+};
+
+#define ADC_CHAN(_idx, _chan_type) { \
+ .type = (_chan_type), \
+ .indexed = 1, \
+ .channel = (_idx), \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
+ BIT(IIO_CHAN_INFO_SAMP_FREQ), \
+ .scan_index = (_idx), \
+ .scan_type = { \
+ .sign = 'u', \
+ .realbits = 12, \
+ .storagebits = 16, \
+ }, \
+}
+
+static const struct iio_chan_spec nxp_sar_adc_iio_channels[] = {
+ ADC_CHAN(0, IIO_VOLTAGE),
+ ADC_CHAN(1, IIO_VOLTAGE),
+ ADC_CHAN(2, IIO_VOLTAGE),
+ ADC_CHAN(3, IIO_VOLTAGE),
+ ADC_CHAN(4, IIO_VOLTAGE),
+ ADC_CHAN(5, IIO_VOLTAGE),
+ ADC_CHAN(6, IIO_VOLTAGE),
+ ADC_CHAN(7, IIO_VOLTAGE),
+ /*
+ * The NXP SAR ADC documentation marks the channels 8 to 31 as
+ * "Reserved". Reflect the same in the driver in case new ADC
+ * variants comes with more channels.
+ */
+ IIO_CHAN_SOFT_TIMESTAMP(32),
+};
+
+static void nxp_sar_adc_irq_cfg(struct nxp_sar_adc *info, bool enable)
+{
+ if (enable)
+ writel(NXP_SAR_ADC_ISR_ECH, NXP_SAR_ADC_IMR(info->regs));
+ else
+ writel(0, NXP_SAR_ADC_IMR(info->regs));
+}
+
+static bool nxp_sar_adc_set_enabled(struct nxp_sar_adc *info, bool enable)
+{
+ u32 mcr;
+ bool pwdn;
+
+ mcr = readl(NXP_SAR_ADC_MCR(info->regs));
+
+ /* Return the current state. */
+ pwdn = FIELD_GET(NXP_SAR_ADC_MCR_PWDN, mcr);
+
+ /* When the enabled flag is not set, we set the power down bit */
+ FIELD_MODIFY(NXP_SAR_ADC_MCR_PWDN, &mcr, !enable);
+
+ writel(mcr, NXP_SAR_ADC_MCR(info->regs));
+
+ /*
+ * Ensure there are at least three cycles between the
+ * configuration of NCMR and the setting of NSTART.
+ */
+ if (enable)
+ ndelay(div64_u64(NSEC_PER_SEC, clk_get_rate(info->clk) * 3));
+
+ return pwdn;
+}
+
+static inline bool nxp_sar_adc_enable(struct nxp_sar_adc *info)
+{
+ return nxp_sar_adc_set_enabled(info, true);
+}
+
+static inline bool nxp_sar_adc_disable(struct nxp_sar_adc *info)
+{
+ return nxp_sar_adc_set_enabled(info, false);
+}
+
+static inline void nxp_sar_adc_calibration_start(void __iomem *base)
+{
+ u32 mcr = readl(NXP_SAR_ADC_MCR(base));
+
+ FIELD_MODIFY(NXP_SAR_ADC_MCR_CALSTART, &mcr, 0x1);
+
+ writel(mcr, NXP_SAR_ADC_MCR(base));
+}
+
+static inline int nxp_sar_adc_calibration_wait(void __iomem *base)
+{
+ u32 msr, ret;
+
+ ret = readl_poll_timeout(NXP_SAR_ADC_MSR(base), msr,
+ !FIELD_GET(NXP_SAR_ADC_MSR_CALBUSY, msr),
+ NXP_SAR_ADC_WAIT_US,
+ NXP_SAR_ADC_CAL_TIMEOUT_US);
+ if (ret)
+ return ret;
+
+ if (FIELD_GET(NXP_SAR_ADC_MSR_CALFAIL, msr)) {
+ /*
+ * If the calibration fails, the status register bit
+ * must be cleared.
+ */
+ FIELD_MODIFY(NXP_SAR_ADC_MSR_CALFAIL, &msr, 0x0);
+ writel(msr, NXP_SAR_ADC_MSR(base));
+
+ return -EAGAIN;
+ }
+
+ return 0;
+}
+
+static int nxp_sar_adc_calibration(struct nxp_sar_adc *info)
+{
+ int ret;
+
+ /* Calibration works only if the adc is powered up. */
+ nxp_sar_adc_enable(info);
+
+ /* The calibration operation starts. */
+ nxp_sar_adc_calibration_start(info->regs);
+
+ ret = nxp_sar_adc_calibration_wait(info->regs);
+
+ /*
+ * Calibration works only if the adc is powered up. However
+ * the calibration is called from the probe function where the
+ * iio is not enabled, so we disable after the calibration.
+ */
+ nxp_sar_adc_disable(info);
+
+ return ret;
+}
+
+static void nxp_sar_adc_conversion_timing_set(struct nxp_sar_adc *info, u32 inpsamp)
+{
+ inpsamp = clamp(inpsamp, NXP_SAR_ADC_CTR_INPSAMP_MIN, NXP_SAR_ADC_CTR_INPSAMP_MAX);
+
+ writel(inpsamp, NXP_SAR_ADC_CTR0(info->regs));
+}
+
+static u32 nxp_sar_adc_conversion_timing_get(struct nxp_sar_adc *info)
+{
+ return readl(NXP_SAR_ADC_CTR0(info->regs));
+}
+
+static void nxp_sar_adc_read_notify(struct nxp_sar_adc *info)
+{
+ writel(NXP_SAR_ADC_CH_MASK, NXP_SAR_ADC_CEOCFR0(info->regs));
+ writel(NXP_SAR_ADC_CH_MASK, NXP_SAR_ADC_CEOCFR1(info->regs));
+}
+
+static int nxp_sar_adc_read_data(struct nxp_sar_adc *info, unsigned int chan)
+{
+ u32 ceocfr, cdr;
+
+ ceocfr = readl(NXP_SAR_ADC_CEOCFR0(info->regs));
+
+ /* FIELD_GET() can not be used here because EOC_CH is not constant */
+ if (!(NXP_SAR_ADC_EOC_CH(chan) & ceocfr))
+ return -EIO;
+
+ cdr = readl(NXP_SAR_ADC_CDR(info->regs, chan));
+ if (!(FIELD_GET(NXP_SAR_ADC_CDR_VALID, cdr)))
+ return -EIO;
+
+ return FIELD_GET(NXP_SAR_ADC_CDR_CDATA_MASK, cdr);
+}
+
+static void nxp_sar_adc_isr_buffer(struct iio_dev *indio_dev)
+{
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+ unsigned int i;
+ int ret;
+
+ for (i = 0; i < info->channels_used; i++) {
+ ret = nxp_sar_adc_read_data(info, info->buffered_chan[i]);
+ if (ret < 0) {
+ nxp_sar_adc_read_notify(info);
+ return;
+ }
+
+ info->buffer[i] = ret;
+ }
+
+ nxp_sar_adc_read_notify(info);
+
+ iio_push_to_buffers_with_ts(indio_dev, info->buffer, sizeof(info->buffer),
+ iio_get_time_ns(indio_dev));
+
+ iio_trigger_notify_done(indio_dev->trig);
+}
+
+static void nxp_sar_adc_isr_read_raw(struct iio_dev *indio_dev)
+{
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+ int ret;
+
+ ret = nxp_sar_adc_read_data(info, info->current_channel);
+ nxp_sar_adc_read_notify(info);
+ if (ret < 0)
+ return;
+
+ info->value = ret;
+ complete(&info->completion);
+}
+
+static irqreturn_t nxp_sar_adc_isr(int irq, void *dev_id)
+{
+ struct iio_dev *indio_dev = (struct iio_dev *)dev_id;
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+ int isr;
+
+ isr = readl(NXP_SAR_ADC_ISR(info->regs));
+ if (!(FIELD_GET(NXP_SAR_ADC_ISR_ECH, isr)))
+ return IRQ_NONE;
+
+ if (iio_buffer_enabled(indio_dev))
+ nxp_sar_adc_isr_buffer(indio_dev);
+ else
+ nxp_sar_adc_isr_read_raw(indio_dev);
+
+ writel(NXP_SAR_ADC_ISR_ECH, NXP_SAR_ADC_ISR(info->regs));
+
+ return IRQ_HANDLED;
+}
+
+static void nxp_sar_adc_channels_disable(struct nxp_sar_adc *info, u32 mask)
+{
+ u32 ncmr, cimr;
+
+ ncmr = readl(NXP_SAR_ADC_NCMR0(info->regs));
+ cimr = readl(NXP_SAR_ADC_CIMR0(info->regs));
+
+ /* FIELD_MODIFY() can not be used because the mask is not constant */
+ ncmr &= ~mask;
+ cimr &= ~mask;
+
+ writel(ncmr, NXP_SAR_ADC_NCMR0(info->regs));
+ writel(cimr, NXP_SAR_ADC_CIMR0(info->regs));
+}
+
+static void nxp_sar_adc_channels_enable(struct nxp_sar_adc *info, u32 mask)
+{
+ u32 ncmr, cimr;
+
+ ncmr = readl(NXP_SAR_ADC_NCMR0(info->regs));
+ cimr = readl(NXP_SAR_ADC_CIMR0(info->regs));
+
+ ncmr |= mask;
+ cimr |= mask;
+
+ writel(ncmr, NXP_SAR_ADC_NCMR0(info->regs));
+ writel(cimr, NXP_SAR_ADC_CIMR0(info->regs));
+}
+
+static void nxp_sar_adc_dma_channels_enable(struct nxp_sar_adc *info, u32 mask)
+{
+ u32 dmar;
+
+ dmar = readl(NXP_SAR_ADC_DMAR0(info->regs));
+
+ dmar |= mask;
+
+ writel(dmar, NXP_SAR_ADC_DMAR0(info->regs));
+}
+
+static void nxp_sar_adc_dma_channels_disable(struct nxp_sar_adc *info, u32 mask)
+{
+ u32 dmar;
+
+ dmar = readl(NXP_SAR_ADC_DMAR0(info->regs));
+
+ dmar &= ~mask;
+
+ writel(dmar, NXP_SAR_ADC_DMAR0(info->regs));
+}
+
+static void nxp_sar_adc_dma_cfg(struct nxp_sar_adc *info, bool enable)
+{
+ u32 dmae;
+
+ dmae = readl(NXP_SAR_ADC_DMAE(info->regs));
+
+ FIELD_MODIFY(NXP_SAR_ADC_DMAE_DMAEN, &dmae, enable);
+
+ writel(dmae, NXP_SAR_ADC_DMAE(info->regs));
+}
+
+static void nxp_sar_adc_stop_conversion(struct nxp_sar_adc *info)
+{
+ u32 mcr;
+
+ mcr = readl(NXP_SAR_ADC_MCR(info->regs));
+
+ FIELD_MODIFY(NXP_SAR_ADC_MCR_NSTART, &mcr, 0x0);
+
+ writel(mcr, NXP_SAR_ADC_MCR(info->regs));
+
+ /*
+ * On disable, we have to wait for the transaction to finish.
+ * ADC does not abort the transaction if a chain conversion
+ * is in progress.
+ * Wait for the worst case scenario - 80 ADC clk cycles.
+ */
+ ndelay(div64_u64(NSEC_PER_SEC, clk_get_rate(info->clk)) * 80U);
+}
+
+static int nxp_sar_adc_start_conversion(struct nxp_sar_adc *info, bool raw)
+{
+ u32 mcr;
+
+ mcr = readl(NXP_SAR_ADC_MCR(info->regs));
+
+ FIELD_MODIFY(NXP_SAR_ADC_MCR_NSTART, &mcr, 0x1);
+ FIELD_MODIFY(NXP_SAR_ADC_MCR_MODE, &mcr, !raw);
+
+ writel(mcr, NXP_SAR_ADC_MCR(info->regs));
+
+ return 0;
+}
+
+static int nxp_sar_adc_read_channel(struct nxp_sar_adc *info, int channel)
+{
+ int ret;
+
+ info->current_channel = channel;
+ nxp_sar_adc_channels_enable(info, BIT(channel));
+ nxp_sar_adc_irq_cfg(info, true);
+ nxp_sar_adc_enable(info);
+
+ reinit_completion(&info->completion);
+ ret = nxp_sar_adc_start_conversion(info, true);
+ if (ret < 0)
+ goto out_disable;
+
+ ret = wait_for_completion_interruptible_timeout(&info->completion,
+ NXP_SAR_ADC_CONV_TIMEOUT_JF);
+ if (ret == 0)
+ ret = -ETIMEDOUT;
+ if (ret > 0)
+ ret = 0;
+
+ nxp_sar_adc_stop_conversion(info);
+
+out_disable:
+ nxp_sar_adc_channels_disable(info, BIT(channel));
+ nxp_sar_adc_irq_cfg(info, false);
+ nxp_sar_adc_disable(info);
+
+ return ret;
+}
+
+static int nxp_sar_adc_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan, int *val,
+ int *val2, long mask)
+{
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+ u32 inpsamp;
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ if (!iio_device_claim_direct(indio_dev))
+ return -EBUSY;
+
+ ret = nxp_sar_adc_read_channel(info, chan->channel);
+
+ iio_device_release_direct(indio_dev);
+
+ if (ret)
+ return ret;
+
+ *val = info->value;
+ return IIO_VAL_INT;
+
+ case IIO_CHAN_INFO_SCALE:
+ *val = info->vref_mV;
+ *val2 = NXP_SAR_ADC_RESOLUTION;
+ return IIO_VAL_FRACTIONAL_LOG2;
+
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ inpsamp = nxp_sar_adc_conversion_timing_get(info);
+ *val = clk_get_rate(info->clk) / (inpsamp + NXP_SAR_ADC_CONV_TIME);
+ return IIO_VAL_INT;
+
+ default:
+ return -EINVAL;
+ }
+}
+
+static int nxp_sar_adc_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
+ int val, int val2, long mask)
+{
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+ u32 inpsamp;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ /*
+ * Configures the sample period duration in terms of the SAR
+ * controller clock. The minimum acceptable value is 8.
+ * Configuring it to a value lower than 8 sets the sample period
+ * to 8 cycles. We read the clock value and divide by the
+ * sampling timing which gives us the number of cycles expected.
+ * The value is 8 bits wide, consequently the max value is 0xFF.
+ */
+ inpsamp = clk_get_rate(info->clk) / val - NXP_SAR_ADC_CONV_TIME;
+ nxp_sar_adc_conversion_timing_set(info, inpsamp);
+ return 0;
+
+ default:
+ return -EINVAL;
+ }
+}
+
+static void nxp_sar_adc_dma_cb(void *data)
+{
+ struct nxp_sar_adc *info = iio_priv(data);
+ struct iio_dev *indio_dev = data;
+ struct dma_tx_state state;
+ struct circ_buf *dma_buf;
+ struct device *dev_dma;
+ u32 *dma_samples;
+ s64 timestamp;
+ int idx, ret;
+
+ guard(spinlock_irqsave)(&info->lock);
+
+ dma_buf = &info->dma_buf;
+ dma_samples = (u32 *)dma_buf->buf;
+ dev_dma = info->dma_chan->device->dev;
+
+ dmaengine_tx_status(info->dma_chan, info->cookie, &state);
+
+ dma_sync_single_for_cpu(dev_dma, info->rx_dma_buf,
+ NXP_SAR_ADC_DMA_BUFF_SZ, DMA_FROM_DEVICE);
+
+ /* Current head position. */
+ dma_buf->head = (NXP_SAR_ADC_DMA_BUFF_SZ - state.residue) /
+ NXP_SAR_ADC_DMA_SAMPLE_SZ;
+
+ /* If everything was transferred, avoid an off by one error. */
+ if (!state.residue)
+ dma_buf->head--;
+
+ /* Something went wrong and nothing transferred. */
+ if (state.residue == NXP_SAR_ADC_DMA_BUFF_SZ)
+ goto out;
+
+ /* Make sure that head is multiple of info->channels_used. */
+ dma_buf->head -= dma_buf->head % info->channels_used;
+
+ /*
+ * dma_buf->tail != dma_buf->head condition will become false
+ * because dma_buf->tail will be incremented with 1.
+ */
+ while (dma_buf->tail != dma_buf->head) {
+ idx = dma_buf->tail % info->channels_used;
+ info->buffer[idx] = dma_samples[dma_buf->tail];
+ dma_buf->tail = (dma_buf->tail + 1) % NXP_SAR_ADC_DMA_SAMPLE_CNT;
+ if (idx != info->channels_used - 1)
+ continue;
+
+ /*
+ * iio_push_to_buffers_with_timestamp should not be
+ * called with dma_samples as parameter. The samples
+ * will be smashed if timestamp is enabled.
+ */
+ timestamp = iio_get_time_ns(indio_dev);
+ ret = iio_push_to_buffers_with_ts(indio_dev, info->buffer,
+ sizeof(info->buffer),
+ timestamp);
+ if (ret < 0 && ret != -EBUSY)
+ dev_err_ratelimited(&indio_dev->dev,
+ "failed to push iio buffer: %d",
+ ret);
+ }
+
+ dma_buf->tail = dma_buf->head;
+out:
+ dma_sync_single_for_device(dev_dma, info->rx_dma_buf,
+ NXP_SAR_ADC_DMA_BUFF_SZ, DMA_FROM_DEVICE);
+}
+
+static int nxp_sar_adc_start_cyclic_dma(struct iio_dev *indio_dev)
+{
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+ struct dma_slave_config config;
+ struct dma_async_tx_descriptor *desc;
+ int ret;
+
+ info->dma_buf.head = 0;
+ info->dma_buf.tail = 0;
+
+ config.direction = DMA_DEV_TO_MEM;
+ config.src_addr_width = NXP_SAR_ADC_DMA_SAMPLE_SZ;
+ config.src_addr = NXP_SAR_ADC_CDR(info->regs_phys, info->buffered_chan[0]);
+ config.src_port_window_size = info->channels_used;
+ config.src_maxburst = info->channels_used;
+ ret = dmaengine_slave_config(info->dma_chan, &config);
+ if (ret < 0)
+ return ret;
+
+ desc = dmaengine_prep_dma_cyclic(info->dma_chan,
+ info->rx_dma_buf,
+ NXP_SAR_ADC_DMA_BUFF_SZ,
+ NXP_SAR_ADC_DMA_BUFF_SZ / 2,
+ DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT);
+ if (!desc)
+ return -EINVAL;
+
+ desc->callback = nxp_sar_adc_dma_cb;
+ desc->callback_param = indio_dev;
+ info->cookie = dmaengine_submit(desc);
+ ret = dma_submit_error(info->cookie);
+ if (ret) {
+ dmaengine_terminate_async(info->dma_chan);
+ return ret;
+ }
+
+ dma_async_issue_pending(info->dma_chan);
+
+ return 0;
+}
+
+static void nxp_sar_adc_buffer_software_do_predisable(struct iio_dev *indio_dev)
+{
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+
+ /*
+ * The ADC DMAEN bit should be cleared before DMA transaction
+ * is canceled.
+ */
+ nxp_sar_adc_stop_conversion(info);
+ dmaengine_terminate_sync(info->dma_chan);
+ nxp_sar_adc_dma_cfg(info, false);
+ nxp_sar_adc_dma_channels_disable(info, *indio_dev->active_scan_mask);
+}
+
+static int nxp_sar_adc_buffer_software_do_postenable(struct iio_dev *indio_dev)
+{
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+ int ret;
+
+ nxp_sar_adc_dma_channels_enable(info, *indio_dev->active_scan_mask);
+
+ nxp_sar_adc_dma_cfg(info, true);
+
+ ret = nxp_sar_adc_start_cyclic_dma(indio_dev);
+ if (ret)
+ goto out_dma_channels_disable;
+
+ ret = nxp_sar_adc_start_conversion(info, false);
+ if (ret)
+ goto out_stop_cyclic_dma;
+
+ return 0;
+
+out_stop_cyclic_dma:
+ dmaengine_terminate_sync(info->dma_chan);
+
+out_dma_channels_disable:
+ nxp_sar_adc_dma_cfg(info, false);
+ nxp_sar_adc_dma_channels_disable(info, *indio_dev->active_scan_mask);
+
+ return ret;
+}
+
+static void nxp_sar_adc_buffer_trigger_do_predisable(struct iio_dev *indio_dev)
+{
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+
+ nxp_sar_adc_irq_cfg(info, false);
+}
+
+static int nxp_sar_adc_buffer_trigger_do_postenable(struct iio_dev *indio_dev)
+{
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+
+ nxp_sar_adc_irq_cfg(info, true);
+
+ return 0;
+}
+
+static int nxp_sar_adc_buffer_postenable(struct iio_dev *indio_dev)
+{
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+ int current_mode = iio_device_get_current_mode(indio_dev);
+ unsigned long channel;
+ int ret;
+
+ info->channels_used = 0;
+
+ /*
+ * The SAR-ADC has two groups of channels.
+ *
+ * - Group #0:
+ * * bit 0-7 : channel 0 -> channel 7
+ * * bit 8-31 : reserved
+ *
+ * - Group #32:
+ * * bit 0-7 : Internal
+ * * bit 8-31 : reserved
+ *
+ * The 8 channels from group #0 are used in this driver for
+ * ADC as described when declaring the IIO device and the
+ * mapping is the same. That means the active_scan_mask can be
+ * used directly to write the channel interrupt mask.
+ */
+ nxp_sar_adc_channels_enable(info, *indio_dev->active_scan_mask);
+
+ for_each_set_bit(channel, indio_dev->active_scan_mask, NXP_SAR_ADC_NR_CHANNELS)
+ info->buffered_chan[info->channels_used++] = channel;
+
+ nxp_sar_adc_enable(info);
+
+ if (current_mode == INDIO_BUFFER_SOFTWARE)
+ ret = nxp_sar_adc_buffer_software_do_postenable(indio_dev);
+ else
+ ret = nxp_sar_adc_buffer_trigger_do_postenable(indio_dev);
+ if (ret)
+ goto out_postenable;
+
+ return 0;
+
+out_postenable:
+ nxp_sar_adc_disable(info);
+ nxp_sar_adc_channels_disable(info, *indio_dev->active_scan_mask);
+
+ return ret;
+}
+
+static int nxp_sar_adc_buffer_predisable(struct iio_dev *indio_dev)
+{
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+ int currentmode = iio_device_get_current_mode(indio_dev);
+
+ if (currentmode == INDIO_BUFFER_SOFTWARE)
+ nxp_sar_adc_buffer_software_do_predisable(indio_dev);
+ else
+ nxp_sar_adc_buffer_trigger_do_predisable(indio_dev);
+
+ nxp_sar_adc_disable(info);
+
+ nxp_sar_adc_channels_disable(info, *indio_dev->active_scan_mask);
+
+ return 0;
+}
+
+static irqreturn_t nxp_sar_adc_trigger_handler(int irq, void *p)
+{
+ struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+ int ret;
+
+ ret = nxp_sar_adc_start_conversion(info, true);
+ if (ret < 0)
+ dev_dbg(&indio_dev->dev, "Failed to start conversion\n");
+
+ return IRQ_HANDLED;
+}
+
+static const struct iio_buffer_setup_ops iio_triggered_buffer_setup_ops = {
+ .postenable = nxp_sar_adc_buffer_postenable,
+ .predisable = nxp_sar_adc_buffer_predisable,
+};
+
+static const struct iio_info nxp_sar_adc_iio_info = {
+ .read_raw = nxp_sar_adc_read_raw,
+ .write_raw = nxp_sar_adc_write_raw,
+};
+
+static int nxp_sar_adc_dma_probe(struct device *dev, struct nxp_sar_adc *info)
+{
+ struct device *dev_dma;
+ u8 *rx_buf;
+
+ info->dma_chan = devm_dma_request_chan(dev, "rx");
+ if (IS_ERR(info->dma_chan))
+ return PTR_ERR(info->dma_chan);
+
+ dev_dma = info->dma_chan->device->dev;
+ rx_buf = dmam_alloc_coherent(dev_dma, NXP_SAR_ADC_DMA_BUFF_SZ,
+ &info->rx_dma_buf, GFP_KERNEL);
+ if (!rx_buf)
+ return -ENOMEM;
+
+ info->dma_buf.buf = rx_buf;
+
+ return 0;
+}
+
+/*
+ * The documentation describes the reset values for the registers.
+ * However some registers do not have these values after a reset. It
+ * is not a desirable situation. In some other SoC family
+ * documentation NXP recommends not assuming the default values are
+ * set and to initialize the registers conforming to the documentation
+ * reset information to prevent this situation. Assume the same rule
+ * applies here as there is a discrepancy between what is read from
+ * the registers at reset time and the documentation.
+ */
+static void nxp_sar_adc_set_default_values(struct nxp_sar_adc *info)
+{
+ writel(0x00003901, NXP_SAR_ADC_MCR(info->regs));
+ writel(0x00000001, NXP_SAR_ADC_MSR(info->regs));
+ writel(0x00000014, NXP_SAR_ADC_CTR0(info->regs));
+ writel(0x00000014, NXP_SAR_ADC_CTR1(info->regs));
+ writel(0x00000000, NXP_SAR_ADC_CIMR0(info->regs));
+ writel(0x00000000, NXP_SAR_ADC_CIMR1(info->regs));
+ writel(0x00000000, NXP_SAR_ADC_NCMR0(info->regs));
+ writel(0x00000000, NXP_SAR_ADC_NCMR1(info->regs));
+}
+
+static int nxp_sar_adc_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ const struct nxp_sar_adc_data *data = device_get_match_data(dev);
+ struct nxp_sar_adc *info;
+ struct iio_dev *indio_dev;
+ struct resource *mem;
+ int irq, ret;
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(*info));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ info = iio_priv(indio_dev);
+
+ info->vref_mV = data->vref_mV;
+
+ info->regs = devm_platform_get_and_ioremap_resource(pdev, 0, &mem);
+ if (IS_ERR(info->regs))
+ return dev_err_probe(dev, PTR_ERR(info->regs),
+ "failed to get and remap resource");
+
+ info->regs_phys = mem->start;
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0)
+ return irq;
+
+ ret = devm_request_irq(dev, irq, nxp_sar_adc_isr, 0,
+ dev_name(dev), indio_dev);
+ if (ret < 0)
+ return dev_err_probe(dev, ret, "failed requesting irq, irq = %d\n", irq);
+
+ spin_lock_init(&info->lock);
+
+ info->clk = devm_clk_get_enabled(dev, NULL);
+ if (IS_ERR(info->clk))
+ return dev_err_probe(dev, PTR_ERR(info->clk),
+ "failed to get the clock\n");
+
+ platform_set_drvdata(pdev, indio_dev);
+
+ init_completion(&info->completion);
+
+ indio_dev->name = data->model;
+ indio_dev->info = &nxp_sar_adc_iio_info;
+ indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
+ indio_dev->channels = nxp_sar_adc_iio_channels;
+ indio_dev->num_channels = ARRAY_SIZE(nxp_sar_adc_iio_channels);
+
+ nxp_sar_adc_set_default_values(info);
+
+ ret = nxp_sar_adc_calibration(info);
+ if (ret)
+ dev_err_probe(dev, ret, "Calibration failed: %d\n", ret);
+
+ ret = nxp_sar_adc_dma_probe(dev, info);
+ if (ret)
+ return dev_err_probe(dev, ret, "Failed to initialize the dma\n");
+
+ ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
+ &iio_pollfunc_store_time,
+ &nxp_sar_adc_trigger_handler,
+ &iio_triggered_buffer_setup_ops);
+ if (ret < 0)
+ return dev_err_probe(dev, ret, "Couldn't initialise the buffer\n");
+
+ ret = devm_iio_device_register(dev, indio_dev);
+ if (ret)
+ return dev_err_probe(dev, ret, "Couldn't register the device\n");
+
+ return 0;
+}
+
+static int nxp_sar_adc_suspend(struct device *dev)
+{
+ struct iio_dev *indio_dev = dev_get_drvdata(dev);
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+
+ info->pwdn = nxp_sar_adc_disable(info);
+ info->inpsamp = nxp_sar_adc_conversion_timing_get(info);
+
+ clk_disable_unprepare(info->clk);
+
+ return 0;
+}
+
+static int nxp_sar_adc_resume(struct device *dev)
+{
+ struct iio_dev *indio_dev = dev_get_drvdata(dev);
+ struct nxp_sar_adc *info = iio_priv(indio_dev);
+ int ret;
+
+ ret = clk_prepare_enable(info->clk);
+ if (ret)
+ return ret;
+
+ nxp_sar_adc_conversion_timing_set(info, info->inpsamp);
+
+ if (!info->pwdn)
+ nxp_sar_adc_enable(info);
+
+ return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(nxp_sar_adc_pm_ops, nxp_sar_adc_suspend, nxp_sar_adc_resume);
+
+static const struct nxp_sar_adc_data s32g2_sar_adc_data = {
+ .vref_mV = 1800,
+ .model = "s32g2-sar-adc"
+};
+
+static const struct of_device_id nxp_sar_adc_match[] = {
+ { .compatible = "nxp,s32g2-sar-adc", .data = &s32g2_sar_adc_data },
+ { }
+};
+MODULE_DEVICE_TABLE(of, nxp_sar_adc_match);
+
+static struct platform_driver nxp_sar_adc_driver = {
+ .probe = nxp_sar_adc_probe,
+ .driver = {
+ .name = "nxp-sar-adc",
+ .of_match_table = nxp_sar_adc_match,
+ .pm = pm_ptr(&nxp_sar_adc_pm_ops),
+ },
+};
+module_platform_driver(nxp_sar_adc_driver);
+
+MODULE_AUTHOR("NXP");
+MODULE_DESCRIPTION("NXP SAR-ADC driver");
+MODULE_LICENSE("GPL");
--
2.43.0