iio: xilinx-xadc: Add basic support for Ultrascale System Monitor

The xilinx-xadc IIO driver currently has support for the XADC in the Xilinx
7 series FPGAs. The system-monitor is the equivalent to the XADC in the
Xilinx UltraScale and UltraScale+ FPGAs.

The IP designers did a good job at maintaining backwards compatibility and
only minor changes are required to add basic support for the system-monitor
core.

The non backwards compatible changes are:
* Register map offset was moved from 0x200 to 0x400
* Only one ADC compared to two in the XADC
* 10 bit ADC instead of 12 bit ADC
* Two of the channels monitor different supplies

Add the necessary logic to accommodate these changes to support the
system-monitor in the XADC driver.

Note that this patch does not include support for some new features found
in the system-monitor like additional alarms, user supply monitoring and
secondary system-monitor access. This might be added at a later time.

Signed-off-by: Lars-Peter Clausen <[e-mail]>
Tested-by: Anand Ashok Dumbre <[e-mail]>
Reviewed-by: Anand Ashok Dumbre <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/adc/Kconfig

···
 	select IIO_BUFFER
 	select IIO_TRIGGERED_BUFFER
 	help
-	  Say yes here to have support for the Xilinx XADC. The driver does support
-	  both the ZYNQ interface to the XADC as well as the AXI-XADC interface.
+	  Say yes here to have support for the Xilinx 7 Series XADC or
+	  UltraScale/UltraScale+ System Management Wizard.
+
+	  For the 7 Series the driver does support both the ZYNQ interface
+	  to the XADC as well as the AXI-XADC interface.
+
+	  The driver also support the Xilinx System Management Wizard IP core
+	  that can be used to access the System Monitor ADC on the Xilinx
+	  UltraScale and UltraScale+ FPGAs.
 
 	  The driver can also be build as a module. If so, the module will be called
 	  xilinx-xadc.

drivers/iio/adc/xilinx-xadc-core.c

···
 #define XADC_AXI_REG_GIER		0x5c
 #define XADC_AXI_REG_IPISR		0x60
 #define XADC_AXI_REG_IPIER		0x68
-#define XADC_AXI_ADC_REG_OFFSET		0x200
+
+/* 7 Series */
+#define XADC_7S_AXI_ADC_REG_OFFSET	0x200
+
+/* UltraScale */
+#define XADC_US_AXI_ADC_REG_OFFSET	0x400
 
 #define XADC_AXI_RESET_MAGIC		0xa
 #define XADC_AXI_GIER_ENABLE		BIT(31)
···
 	.get_dclk_rate = xadc_zynq_get_dclk_rate,
 	.interrupt_handler = xadc_zynq_interrupt_handler,
 	.update_alarm = xadc_zynq_update_alarm,
+	.type = XADC_TYPE_S7,
+};
+
+static const unsigned int xadc_axi_reg_offsets[] = {
+	[XADC_TYPE_S7] = XADC_7S_AXI_ADC_REG_OFFSET,
+	[XADC_TYPE_US] = XADC_US_AXI_ADC_REG_OFFSET,
 };
 
 static int xadc_axi_read_adc_reg(struct xadc *xadc, unsigned int reg,
···
 {
 	uint32_t val32;
 
-	xadc_read_reg(xadc, XADC_AXI_ADC_REG_OFFSET + reg * 4, &val32);
+	xadc_read_reg(xadc, xadc_axi_reg_offsets[xadc->ops->type] + reg * 4,
+		&val32);
 	*val = val32 & 0xffff;
 
 	return 0;
···
 static int xadc_axi_write_adc_reg(struct xadc *xadc, unsigned int reg,
 	uint16_t val)
 {
-	xadc_write_reg(xadc, XADC_AXI_ADC_REG_OFFSET + reg * 4, val);
+	xadc_write_reg(xadc, xadc_axi_reg_offsets[xadc->ops->type] + reg * 4,
+		val);
 
 	return 0;
 }
···
 	return clk_get_rate(xadc->clk);
 }
 
-static const struct xadc_ops xadc_axi_ops = {
+static const struct xadc_ops xadc_7s_axi_ops = {
 	.read = xadc_axi_read_adc_reg,
 	.write = xadc_axi_write_adc_reg,
 	.setup = xadc_axi_setup,
···
 	.update_alarm = xadc_axi_update_alarm,
 	.interrupt_handler = xadc_axi_interrupt_handler,
 	.flags = XADC_FLAGS_BUFFERED,
+	.type = XADC_TYPE_S7,
+};
+
+static const struct xadc_ops xadc_us_axi_ops = {
+	.read = xadc_axi_read_adc_reg,
+	.write = xadc_axi_write_adc_reg,
+	.setup = xadc_axi_setup,
+	.get_dclk_rate = xadc_axi_get_dclk,
+	.update_alarm = xadc_axi_update_alarm,
+	.interrupt_handler = xadc_axi_interrupt_handler,
+	.flags = XADC_FLAGS_BUFFERED,
+	.type = XADC_TYPE_US,
 };
 
 static int _xadc_update_adc_reg(struct xadc *xadc, unsigned int reg,
···
 {
 	uint16_t val;
 
+	/*
+	 * As per datasheet the power-down bits are don't care in the
+	 * UltraScale, but as per reality setting the power-down bit for the
+	 * non-existing ADC-B powers down the main ADC, so just return and don't
+	 * do anything.
+	 */
+	if (xadc->ops->type == XADC_TYPE_US)
+		return 0;
+
 	/* Powerdown the ADC-B when it is not needed. */
 	switch (seq_mode) {
 	case XADC_CONF1_SEQ_SIMULTANEOUS:
···
 static int xadc_get_seq_mode(struct xadc *xadc, unsigned long scan_mode)
 {
 	unsigned int aux_scan_mode = scan_mode >> 16;
+
+	/* UltraScale has only one ADC and supports only continuous mode */
+	if (xadc->ops->type == XADC_TYPE_US)
+		return XADC_CONF1_SEQ_CONTINUOUS;
 
 	if (xadc->external_mux_mode == XADC_EXTERNAL_MUX_DUAL)
 		return XADC_CONF1_SEQ_SIMULTANEOUS;
···
 	struct iio_chan_spec const *chan, int *val, int *val2, long info)
 {
 	struct xadc *xadc = iio_priv(indio_dev);
+	unsigned int bits = chan->scan_type.realbits;
 	uint16_t val16;
 	int ret;
 
···
 		if (ret < 0)
 			return ret;
 
-		val16 >>= 4;
+		val16 >>= chan->scan_type.shift;
 		if (chan->scan_type.sign == 'u')
 			*val = val16;
 		else
-			*val = sign_extend32(val16, 11);
+			*val = sign_extend32(val16, bits - 1);
 
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		switch (chan->type) {
 		case IIO_VOLTAGE:
-			/* V = (val * 3.0) / 4096 */
+			/* V = (val * 3.0) / 2**bits */
 			switch (chan->address) {
 			case XADC_REG_VCCINT:
 			case XADC_REG_VCCAUX:
···
 				*val = 1000;
 				break;
 			}
-			*val2 = 12;
+			*val2 = chan->scan_type.realbits;
 			return IIO_VAL_FRACTIONAL_LOG2;
 		case IIO_TEMP:
-			/* Temp in C = (val * 503.975) / 4096 - 273.15 */
+			/* Temp in C = (val * 503.975) / 2**bits - 273.15 */
 			*val = 503975;
-			*val2 = 12;
+			*val2 = bits;
 			return IIO_VAL_FRACTIONAL_LOG2;
 		default:
 			return -EINVAL;
 		}
 	case IIO_CHAN_INFO_OFFSET:
 		/* Only the temperature channel has an offset */
-		*val = -((273150 << 12) / 503975);
+		*val = -((273150 << bits) / 503975);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		ret = xadc_read_samplerate(xadc);
···
 	},
 };
 
-#define XADC_CHAN_TEMP(_chan, _scan_index, _addr) { \
+#define XADC_CHAN_TEMP(_chan, _scan_index, _addr, _bits) { \
 	.type = IIO_TEMP, \
 	.indexed = 1, \
 	.channel = (_chan), \
···
 	.scan_index = (_scan_index), \
 	.scan_type = { \
 		.sign = 'u', \
-		.realbits = 12, \
+		.realbits = (_bits), \
 		.storagebits = 16, \
-		.shift = 4, \
+		.shift = 16 - (_bits), \
 		.endianness = IIO_CPU, \
 	}, \
 }
 
-#define XADC_CHAN_VOLTAGE(_chan, _scan_index, _addr, _ext, _alarm) { \
+#define XADC_CHAN_VOLTAGE(_chan, _scan_index, _addr, _bits, _ext, _alarm) { \
 	.type = IIO_VOLTAGE, \
 	.indexed = 1, \
 	.channel = (_chan), \
···
 	.scan_index = (_scan_index), \
 	.scan_type = { \
 		.sign = ((_addr) == XADC_REG_VREFN) ? 's' : 'u', \
-		.realbits = 12, \
+		.realbits = (_bits), \
 		.storagebits = 16, \
-		.shift = 4, \
+		.shift = 16 - (_bits), \
 		.endianness = IIO_CPU, \
 	}, \
 	.extend_name = _ext, \
 }
 
-static const struct iio_chan_spec xadc_channels[] = {
-	XADC_CHAN_TEMP(0, 8, XADC_REG_TEMP),
-	XADC_CHAN_VOLTAGE(0, 9, XADC_REG_VCCINT, "vccint", true),
-	XADC_CHAN_VOLTAGE(1, 10, XADC_REG_VCCAUX, "vccaux", true),
-	XADC_CHAN_VOLTAGE(2, 14, XADC_REG_VCCBRAM, "vccbram", true),
-	XADC_CHAN_VOLTAGE(3, 5, XADC_REG_VCCPINT, "vccpint", true),
-	XADC_CHAN_VOLTAGE(4, 6, XADC_REG_VCCPAUX, "vccpaux", true),
-	XADC_CHAN_VOLTAGE(5, 7, XADC_REG_VCCO_DDR, "vccoddr", true),
-	XADC_CHAN_VOLTAGE(6, 12, XADC_REG_VREFP, "vrefp", false),
-	XADC_CHAN_VOLTAGE(7, 13, XADC_REG_VREFN, "vrefn", false),
-	XADC_CHAN_VOLTAGE(8, 11, XADC_REG_VPVN, NULL, false),
-	XADC_CHAN_VOLTAGE(9, 16, XADC_REG_VAUX(0), NULL, false),
-	XADC_CHAN_VOLTAGE(10, 17, XADC_REG_VAUX(1), NULL, false),
-	XADC_CHAN_VOLTAGE(11, 18, XADC_REG_VAUX(2), NULL, false),
-	XADC_CHAN_VOLTAGE(12, 19, XADC_REG_VAUX(3), NULL, false),
-	XADC_CHAN_VOLTAGE(13, 20, XADC_REG_VAUX(4), NULL, false),
-	XADC_CHAN_VOLTAGE(14, 21, XADC_REG_VAUX(5), NULL, false),
-	XADC_CHAN_VOLTAGE(15, 22, XADC_REG_VAUX(6), NULL, false),
-	XADC_CHAN_VOLTAGE(16, 23, XADC_REG_VAUX(7), NULL, false),
-	XADC_CHAN_VOLTAGE(17, 24, XADC_REG_VAUX(8), NULL, false),
-	XADC_CHAN_VOLTAGE(18, 25, XADC_REG_VAUX(9), NULL, false),
-	XADC_CHAN_VOLTAGE(19, 26, XADC_REG_VAUX(10), NULL, false),
-	XADC_CHAN_VOLTAGE(20, 27, XADC_REG_VAUX(11), NULL, false),
-	XADC_CHAN_VOLTAGE(21, 28, XADC_REG_VAUX(12), NULL, false),
-	XADC_CHAN_VOLTAGE(22, 29, XADC_REG_VAUX(13), NULL, false),
-	XADC_CHAN_VOLTAGE(23, 30, XADC_REG_VAUX(14), NULL, false),
-	XADC_CHAN_VOLTAGE(24, 31, XADC_REG_VAUX(15), NULL, false),
+/* 7 Series */
+#define XADC_7S_CHAN_TEMP(_chan, _scan_index, _addr) \
+	XADC_CHAN_TEMP(_chan, _scan_index, _addr, 12)
+#define XADC_7S_CHAN_VOLTAGE(_chan, _scan_index, _addr, _ext, _alarm) \
+	XADC_CHAN_VOLTAGE(_chan, _scan_index, _addr, 12, _ext, _alarm)
+
+static const struct iio_chan_spec xadc_7s_channels[] = {
+	XADC_7S_CHAN_TEMP(0, 8, XADC_REG_TEMP),
+	XADC_7S_CHAN_VOLTAGE(0, 9, XADC_REG_VCCINT, "vccint", true),
+	XADC_7S_CHAN_VOLTAGE(1, 10, XADC_REG_VCCAUX, "vccaux", true),
+	XADC_7S_CHAN_VOLTAGE(2, 14, XADC_REG_VCCBRAM, "vccbram", true),
+	XADC_7S_CHAN_VOLTAGE(3, 5, XADC_REG_VCCPINT, "vccpint", true),
+	XADC_7S_CHAN_VOLTAGE(4, 6, XADC_REG_VCCPAUX, "vccpaux", true),
+	XADC_7S_CHAN_VOLTAGE(5, 7, XADC_REG_VCCO_DDR, "vccoddr", true),
+	XADC_7S_CHAN_VOLTAGE(6, 12, XADC_REG_VREFP, "vrefp", false),
+	XADC_7S_CHAN_VOLTAGE(7, 13, XADC_REG_VREFN, "vrefn", false),
+	XADC_7S_CHAN_VOLTAGE(8, 11, XADC_REG_VPVN, NULL, false),
+	XADC_7S_CHAN_VOLTAGE(9, 16, XADC_REG_VAUX(0), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(10, 17, XADC_REG_VAUX(1), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(11, 18, XADC_REG_VAUX(2), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(12, 19, XADC_REG_VAUX(3), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(13, 20, XADC_REG_VAUX(4), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(14, 21, XADC_REG_VAUX(5), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(15, 22, XADC_REG_VAUX(6), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(16, 23, XADC_REG_VAUX(7), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(17, 24, XADC_REG_VAUX(8), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(18, 25, XADC_REG_VAUX(9), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(19, 26, XADC_REG_VAUX(10), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(20, 27, XADC_REG_VAUX(11), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(21, 28, XADC_REG_VAUX(12), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(22, 29, XADC_REG_VAUX(13), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(23, 30, XADC_REG_VAUX(14), NULL, false),
+	XADC_7S_CHAN_VOLTAGE(24, 31, XADC_REG_VAUX(15), NULL, false),
+};
+
+/* UltraScale */
+#define XADC_US_CHAN_TEMP(_chan, _scan_index, _addr) \
+	XADC_CHAN_TEMP(_chan, _scan_index, _addr, 10)
+#define XADC_US_CHAN_VOLTAGE(_chan, _scan_index, _addr, _ext, _alarm) \
+	XADC_CHAN_VOLTAGE(_chan, _scan_index, _addr, 10, _ext, _alarm)
+
+static const struct iio_chan_spec xadc_us_channels[] = {
+	XADC_US_CHAN_TEMP(0, 8, XADC_REG_TEMP),
+	XADC_US_CHAN_VOLTAGE(0, 9, XADC_REG_VCCINT, "vccint", true),
+	XADC_US_CHAN_VOLTAGE(1, 10, XADC_REG_VCCAUX, "vccaux", true),
+	XADC_US_CHAN_VOLTAGE(2, 14, XADC_REG_VCCBRAM, "vccbram", true),
+	XADC_US_CHAN_VOLTAGE(3, 5, XADC_REG_VCCPINT, "vccpsintlp", true),
+	XADC_US_CHAN_VOLTAGE(4, 6, XADC_REG_VCCPAUX, "vccpsintfp", true),
+	XADC_US_CHAN_VOLTAGE(5, 7, XADC_REG_VCCO_DDR, "vccpsaux", true),
+	XADC_US_CHAN_VOLTAGE(6, 12, XADC_REG_VREFP, "vrefp", false),
+	XADC_US_CHAN_VOLTAGE(7, 13, XADC_REG_VREFN, "vrefn", false),
+	XADC_US_CHAN_VOLTAGE(8, 11, XADC_REG_VPVN, NULL, false),
+	XADC_US_CHAN_VOLTAGE(9, 16, XADC_REG_VAUX(0), NULL, false),
+	XADC_US_CHAN_VOLTAGE(10, 17, XADC_REG_VAUX(1), NULL, false),
+	XADC_US_CHAN_VOLTAGE(11, 18, XADC_REG_VAUX(2), NULL, false),
+	XADC_US_CHAN_VOLTAGE(12, 19, XADC_REG_VAUX(3), NULL, false),
+	XADC_US_CHAN_VOLTAGE(13, 20, XADC_REG_VAUX(4), NULL, false),
+	XADC_US_CHAN_VOLTAGE(14, 21, XADC_REG_VAUX(5), NULL, false),
+	XADC_US_CHAN_VOLTAGE(15, 22, XADC_REG_VAUX(6), NULL, false),
+	XADC_US_CHAN_VOLTAGE(16, 23, XADC_REG_VAUX(7), NULL, false),
+	XADC_US_CHAN_VOLTAGE(17, 24, XADC_REG_VAUX(8), NULL, false),
+	XADC_US_CHAN_VOLTAGE(18, 25, XADC_REG_VAUX(9), NULL, false),
+	XADC_US_CHAN_VOLTAGE(19, 26, XADC_REG_VAUX(10), NULL, false),
+	XADC_US_CHAN_VOLTAGE(20, 27, XADC_REG_VAUX(11), NULL, false),
+	XADC_US_CHAN_VOLTAGE(21, 28, XADC_REG_VAUX(12), NULL, false),
+	XADC_US_CHAN_VOLTAGE(22, 29, XADC_REG_VAUX(13), NULL, false),
+	XADC_US_CHAN_VOLTAGE(23, 30, XADC_REG_VAUX(14), NULL, false),
+	XADC_US_CHAN_VOLTAGE(24, 31, XADC_REG_VAUX(15), NULL, false),
 };
 
 static const struct iio_info xadc_info = {
···
 };
 
 static const struct of_device_id xadc_of_match_table[] = {
-	{ .compatible = "xlnx,zynq-xadc-1.00.a", (void *)&xadc_zynq_ops },
-	{ .compatible = "xlnx,axi-xadc-1.00.a", (void *)&xadc_axi_ops },
+	{
+		.compatible = "xlnx,zynq-xadc-1.00.a",
+		.data = &xadc_zynq_ops
+	}, {
+		.compatible = "xlnx,axi-xadc-1.00.a",
+		.data = &xadc_7s_axi_ops
+	}, {
+		.compatible = "xlnx,system-management-wiz-1.3",
+		.data = &xadc_us_axi_ops
+	},
 	{ },
 };
 MODULE_DEVICE_TABLE(of, xadc_of_match_table);
···
 {
 	struct device *dev = indio_dev->dev.parent;
 	struct xadc *xadc = iio_priv(indio_dev);
+	const struct iio_chan_spec *channel_templates;
 	struct iio_chan_spec *channels, *chan;
 	struct device_node *chan_node, *child;
+	unsigned int max_channels;
 	unsigned int num_channels;
 	const char *external_mux;
 	u32 ext_mux_chan;
···
 
 		*conf |= XADC_CONF0_MUX | XADC_CONF0_CHAN(ext_mux_chan);
 	}
-
-	channels = devm_kmemdup(dev, xadc_channels,
-				sizeof(xadc_channels), GFP_KERNEL);
+	if (xadc->ops->type == XADC_TYPE_S7) {
+		channel_templates = xadc_7s_channels;
+		max_channels = ARRAY_SIZE(xadc_7s_channels);
+	} else {
+		channel_templates = xadc_us_channels;
+		max_channels = ARRAY_SIZE(xadc_us_channels);
+	}
+	channels = devm_kmemdup(dev, channel_templates,
+				sizeof(channels[0]) * max_channels, GFP_KERNEL);
 	if (!channels)
 		return -ENOMEM;
 
···
 	chan_node = of_get_child_by_name(np, "xlnx,channels");
 	if (chan_node) {
 		for_each_child_of_node(chan_node, child) {
-			if (num_channels >= ARRAY_SIZE(xadc_channels)) {
+			if (num_channels >= max_channels) {
 				of_node_put(child);
 				break;
 			}
···
 
 	return 0;
 }
+
+static const char * const xadc_type_names[] = {
+	[XADC_TYPE_S7] = "xadc",
+	[XADC_TYPE_US] = "xilinx-system-monitor",
+};
 
 static int xadc_probe(struct platform_device *pdev)
 {
···
 	if (IS_ERR(xadc->base))
 		return PTR_ERR(xadc->base);
 
-	indio_dev->name = "xadc";
+	indio_dev->name = xadc_type_names[xadc->ops->type];
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->info = &xadc_info;
 

drivers/iio/adc/xilinx-xadc-events.c

···
 	return ret;
 }
 
-/* Register value is msb aligned, the lower 4 bits are ignored */
-#define XADC_THRESHOLD_VALUE_SHIFT 4
-
 int xadc_read_event_value(struct iio_dev *indio_dev,
 	const struct iio_chan_spec *chan, enum iio_event_type type,
 	enum iio_event_direction dir, enum iio_event_info info,
···
 		return -EINVAL;
 	}
 
-	*val >>= XADC_THRESHOLD_VALUE_SHIFT;
+	/* MSB aligned */
+	*val >>= 16 - chan->scan_type.realbits;
 
 	return IIO_VAL_INT;
 }
···
 	struct xadc *xadc = iio_priv(indio_dev);
 	int ret = 0;
 
-	val <<= XADC_THRESHOLD_VALUE_SHIFT;
+	/* MSB aligned */
+	val <<= 16 - chan->scan_type.realbits;
 
 	if (val < 0 || val > 0xffff)
 		return -EINVAL;

drivers/iio/adc/xilinx-xadc.h

···
 	int irq;
 };
 
+enum xadc_type {
+	XADC_TYPE_S7, /* Series 7 */
+	XADC_TYPE_US, /* UltraScale and UltraScale+ */
+};
+
 struct xadc_ops {
 	int (*read)(struct xadc *xadc, unsigned int reg, uint16_t *val);
 	int (*write)(struct xadc *xadc, unsigned int reg, uint16_t val);
···
 	irqreturn_t (*interrupt_handler)(int irq, void *devid);
 
 	unsigned int flags;
+	enum xadc_type type;
 };
 
 static inline int _xadc_read_adc_reg(struct xadc *xadc, unsigned int reg,