9 files changed, 560 insertions, 19 deletions

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 11841f4b7b2b..0b79c5d04cc9 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -99,6 +99,15 @@ config MFD_AAT2870_CORE
 	  additional drivers must be enabled in order to use the
 	  functionality of the device.
 
+config MFD_AT91_USART
+	tristate "AT91 USART Driver"
+	select MFD_CORE
+	help
+	  Select this to get support for AT91 USART IP. This is a wrapper
+	  over at91-usart-serial driver and usart-spi-driver. Only one function
+	  can be used at a time. The choice is done at boot time by the probe
+	  function of this MFD driver according to a device tree property.
+
 config MFD_ATMEL_FLEXCOM
 	tristate "Atmel Flexcom (Flexible Serial Communication Unit)"
 	select MFD_CORE
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 5856a9489cbd..12980a4ad460 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -196,6 +196,7 @@ obj-$(CONFIG_MFD_SPMI_PMIC)	+= qcom-spmi-pmic.o
 obj-$(CONFIG_TPS65911_COMPARATOR)	+= tps65911-comparator.o
 obj-$(CONFIG_MFD_TPS65090)	+= tps65090.o
 obj-$(CONFIG_MFD_AAT2870_CORE)	+= aat2870-core.o
+obj-$(CONFIG_MFD_AT91_USART)	+= at91-usart.o
 obj-$(CONFIG_MFD_ATMEL_FLEXCOM)	+= atmel-flexcom.o
 obj-$(CONFIG_MFD_ATMEL_HLCDC)	+= atmel-hlcdc.o
 obj-$(CONFIG_MFD_ATMEL_SMC)	+= atmel-smc.o
diff --git a/drivers/mfd/at91-usart.c b/drivers/mfd/at91-usart.c
new file mode 100644
index 000000000000..d20747f612c1
--- /dev/null
+++ b/drivers/mfd/at91-usart.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for AT91 USART
+ *
+ * Copyright (C) 2018 Microchip Technology
+ *
+ * Author: Radu Pirea <radu.pirea@microchip.com>
+ *
+ */
+
+#include <dt-bindings/mfd/at91-usart.h>
+
+#include <linux/module.h>
+#include <linux/mfd/core.h>
+#include <linux/of.h>
+#include <linux/property.h>
+
+static struct mfd_cell at91_usart_spi_subdev = {
+		.name = "at91_usart_spi",
+		.of_compatible = "microchip,at91sam9g45-usart-spi",
+	};
+
+static struct mfd_cell at91_usart_serial_subdev = {
+		.name = "atmel_usart_serial",
+		.of_compatible = "atmel,at91rm9200-usart-serial",
+	};
+
+static int at91_usart_mode_probe(struct platform_device *pdev)
+{
+	struct mfd_cell cell;
+	u32 opmode = AT91_USART_MODE_SERIAL;
+
+	device_property_read_u32(&pdev->dev, "atmel,usart-mode", &opmode);
+
+	switch (opmode) {
+	case AT91_USART_MODE_SPI:
+		cell = at91_usart_spi_subdev;
+		break;
+	case AT91_USART_MODE_SERIAL:
+		cell = at91_usart_serial_subdev;
+		break;
+	default:
+		dev_err(&pdev->dev, "atmel,usart-mode has an invalid value %u\n",
+			opmode);
+		return -EINVAL;
+	}
+
+	return devm_mfd_add_devices(&pdev->dev, PLATFORM_DEVID_AUTO, &cell, 1,
+			      NULL, 0, NULL);
+}
+
+static const struct of_device_id at91_usart_mode_of_match[] = {
+	{ .compatible = "atmel,at91rm9200-usart" },
+	{ .compatible = "atmel,at91sam9260-usart" },
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, at91_usart_mode_of_match);
+
+static struct platform_driver at91_usart_mfd = {
+	.probe	= at91_usart_mode_probe,
+	.driver	= {
+		.name		= "at91_usart_mode",
+		.of_match_table	= at91_usart_mode_of_match,
+	},
+};
+
+module_platform_driver(at91_usart_mfd);
+
+MODULE_AUTHOR("Radu Pirea <radu.pirea@microchip.com>");
+MODULE_DESCRIPTION("AT91 USART MFD driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/mfd/menelaus.c b/drivers/mfd/menelaus.c
index 29b7164a823b..d28ebe7ecd21 100644
--- a/drivers/mfd/menelaus.c
+++ b/drivers/mfd/menelaus.c
@@ -1094,6 +1094,7 @@ static void menelaus_rtc_alarm_work(struct menelaus_chip *m)
 static inline void menelaus_rtc_init(struct menelaus_chip *m)
 {
 	int	alarm = (m->client->irq > 0);
+	int	err;
 
 	/* assume 32KDETEN pin is pulled high */
 	if (!(menelaus_read_reg(MENELAUS_OSC_CTRL) & 0x80)) {
@@ -1101,6 +1102,12 @@ static inline void menelaus_rtc_init(struct menelaus_chip *m)
 		return;
 	}
 
+	m->rtc = devm_rtc_allocate_device(&m->client->dev);
+	if (IS_ERR(m->rtc))
+		return;
+
+	m->rtc->ops = &menelaus_rtc_ops;
+
 	/* support RTC alarm; it can issue wakeups */
 	if (alarm) {
 		if (menelaus_add_irq_work(MENELAUS_RTCALM_IRQ,
@@ -1125,10 +1132,8 @@ static inline void menelaus_rtc_init(struct menelaus_chip *m)
 		menelaus_write_reg(MENELAUS_RTC_CTRL, m->rtc_control);
 	}
 
-	m->rtc = rtc_device_register(DRIVER_NAME,
-			&m->client->dev,
-			&menelaus_rtc_ops, THIS_MODULE);
-	if (IS_ERR(m->rtc)) {
+	err = rtc_register_device(m->rtc);
+	if (err) {
 		if (alarm) {
 			menelaus_remove_irq_work(MENELAUS_RTCALM_IRQ);
 			device_init_wakeup(&m->client->dev, 0);
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 671d078349cc..2e259d0f4136 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -83,6 +83,14 @@ config SPI_ATMEL
 	  This selects a driver for the Atmel SPI Controller, present on
 	  many AT91 ARM chips.
 
+config SPI_AT91_USART
+	tristate "Atmel USART Controller SPI driver"
+	depends on (ARCH_AT91 || COMPILE_TEST)
+	depends on MFD_AT91_USART
+	help
+	  This selects a driver for the AT91 USART Controller as SPI Master,
+	  present on AT91 and SAMA5 SoC series.
+
 config SPI_AU1550
 	tristate "Au1550/Au1200/Au1300 SPI Controller"
 	depends on MIPS_ALCHEMY
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index a90d55970036..ad094fca36aa 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_SPI_LOOPBACK_TEST)		+= spi-loopback-test.o
 obj-$(CONFIG_SPI_ALTERA)		+= spi-altera.o
 obj-$(CONFIG_SPI_ARMADA_3700)		+= spi-armada-3700.o
 obj-$(CONFIG_SPI_ATMEL)			+= spi-atmel.o
+obj-$(CONFIG_SPI_AT91_USART)		+= spi-at91-usart.o
 obj-$(CONFIG_SPI_ATH79)			+= spi-ath79.o
 obj-$(CONFIG_SPI_AU1550)		+= spi-au1550.o
 obj-$(CONFIG_SPI_AXI_SPI_ENGINE)	+= spi-axi-spi-engine.o
diff --git a/drivers/spi/spi-at91-usart.c b/drivers/spi/spi-at91-usart.c
new file mode 100644
index 000000000000..a924657642fa
--- /dev/null
+++ b/drivers/spi/spi-at91-usart.c
@@ -0,0 +1,432 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Driver for AT91 USART Controllers as SPI
+//
+// Copyright (C) 2018 Microchip Technology Inc.
+//
+// Author: Radu Pirea <radu.pirea@microchip.com>
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_device.h>
+
+#include <linux/spi/spi.h>
+
+#define US_CR			0x00
+#define US_MR			0x04
+#define US_IER			0x08
+#define US_IDR			0x0C
+#define US_CSR			0x14
+#define US_RHR			0x18
+#define US_THR			0x1C
+#define US_BRGR			0x20
+#define US_VERSION		0xFC
+
+#define US_CR_RSTRX		BIT(2)
+#define US_CR_RSTTX		BIT(3)
+#define US_CR_RXEN		BIT(4)
+#define US_CR_RXDIS		BIT(5)
+#define US_CR_TXEN		BIT(6)
+#define US_CR_TXDIS		BIT(7)
+
+#define US_MR_SPI_MASTER	0x0E
+#define US_MR_CHRL		GENMASK(7, 6)
+#define US_MR_CPHA		BIT(8)
+#define US_MR_CPOL		BIT(16)
+#define US_MR_CLKO		BIT(18)
+#define US_MR_WRDBT		BIT(20)
+#define US_MR_LOOP		BIT(15)
+
+#define US_IR_RXRDY		BIT(0)
+#define US_IR_TXRDY		BIT(1)
+#define US_IR_OVRE		BIT(5)
+
+#define US_BRGR_SIZE		BIT(16)
+
+#define US_MIN_CLK_DIV		0x06
+#define US_MAX_CLK_DIV		BIT(16)
+
+#define US_RESET		(US_CR_RSTRX | US_CR_RSTTX)
+#define US_DISABLE		(US_CR_RXDIS | US_CR_TXDIS)
+#define US_ENABLE		(US_CR_RXEN | US_CR_TXEN)
+#define US_OVRE_RXRDY_IRQS	(US_IR_OVRE | US_IR_RXRDY)
+
+#define US_INIT \
+	(US_MR_SPI_MASTER | US_MR_CHRL | US_MR_CLKO | US_MR_WRDBT)
+
+/* Register access macros */
+#define at91_usart_spi_readl(port, reg) \
+	readl_relaxed((port)->regs + US_##reg)
+#define at91_usart_spi_writel(port, reg, value) \
+	writel_relaxed((value), (port)->regs + US_##reg)
+
+#define at91_usart_spi_readb(port, reg) \
+	readb_relaxed((port)->regs + US_##reg)
+#define at91_usart_spi_writeb(port, reg, value) \
+	writeb_relaxed((value), (port)->regs + US_##reg)
+
+struct at91_usart_spi {
+	struct spi_transfer	*current_transfer;
+	void __iomem		*regs;
+	struct device		*dev;
+	struct clk		*clk;
+
+	/*used in interrupt to protect data reading*/
+	spinlock_t		lock;
+
+	int			irq;
+	unsigned int		current_tx_remaining_bytes;
+	unsigned int		current_rx_remaining_bytes;
+
+	u32			spi_clk;
+	u32			status;
+
+	bool			xfer_failed;
+};
+
+static inline u32 at91_usart_spi_tx_ready(struct at91_usart_spi *aus)
+{
+	return aus->status & US_IR_TXRDY;
+}
+
+static inline u32 at91_usart_spi_rx_ready(struct at91_usart_spi *aus)
+{
+	return aus->status & US_IR_RXRDY;
+}
+
+static inline u32 at91_usart_spi_check_overrun(struct at91_usart_spi *aus)
+{
+	return aus->status & US_IR_OVRE;
+}
+
+static inline u32 at91_usart_spi_read_status(struct at91_usart_spi *aus)
+{
+	aus->status = at91_usart_spi_readl(aus, CSR);
+	return aus->status;
+}
+
+static inline void at91_usart_spi_tx(struct at91_usart_spi *aus)
+{
+	unsigned int len = aus->current_transfer->len;
+	unsigned int remaining = aus->current_tx_remaining_bytes;
+	const u8  *tx_buf = aus->current_transfer->tx_buf;
+
+	if (!remaining)
+		return;
+
+	if (at91_usart_spi_tx_ready(aus)) {
+		at91_usart_spi_writeb(aus, THR, tx_buf[len - remaining]);
+		aus->current_tx_remaining_bytes--;
+	}
+}
+
+static inline void at91_usart_spi_rx(struct at91_usart_spi *aus)
+{
+	int len = aus->current_transfer->len;
+	int remaining = aus->current_rx_remaining_bytes;
+	u8  *rx_buf = aus->current_transfer->rx_buf;
+
+	if (!remaining)
+		return;
+
+	rx_buf[len - remaining] = at91_usart_spi_readb(aus, RHR);
+	aus->current_rx_remaining_bytes--;
+}
+
+static inline void
+at91_usart_spi_set_xfer_speed(struct at91_usart_spi *aus,
+			      struct spi_transfer *xfer)
+{
+	at91_usart_spi_writel(aus, BRGR,
+			      DIV_ROUND_UP(aus->spi_clk, xfer->speed_hz));
+}
+
+static irqreturn_t at91_usart_spi_interrupt(int irq, void *dev_id)
+{
+	struct spi_controller *controller = dev_id;
+	struct at91_usart_spi *aus = spi_master_get_devdata(controller);
+
+	spin_lock(&aus->lock);
+	at91_usart_spi_read_status(aus);
+
+	if (at91_usart_spi_check_overrun(aus)) {
+		aus->xfer_failed = true;
+		at91_usart_spi_writel(aus, IDR, US_IR_OVRE | US_IR_RXRDY);
+		spin_unlock(&aus->lock);
+		return IRQ_HANDLED;
+	}
+
+	if (at91_usart_spi_rx_ready(aus)) {
+		at91_usart_spi_rx(aus);
+		spin_unlock(&aus->lock);
+		return IRQ_HANDLED;
+	}
+
+	spin_unlock(&aus->lock);
+
+	return IRQ_NONE;
+}
+
+static int at91_usart_spi_setup(struct spi_device *spi)
+{
+	struct at91_usart_spi *aus = spi_master_get_devdata(spi->controller);
+	u32 *ausd = spi->controller_state;
+	unsigned int mr = at91_usart_spi_readl(aus, MR);
+	u8 bits = spi->bits_per_word;
+
+	if (bits != 8) {
+		dev_dbg(&spi->dev, "Only 8 bits per word are supported\n");
+		return -EINVAL;
+	}
+
+	if (spi->mode & SPI_CPOL)
+		mr |= US_MR_CPOL;
+	else
+		mr &= ~US_MR_CPOL;
+
+	if (spi->mode & SPI_CPHA)
+		mr |= US_MR_CPHA;
+	else
+		mr &= ~US_MR_CPHA;
+
+	if (spi->mode & SPI_LOOP)
+		mr |= US_MR_LOOP;
+	else
+		mr &= ~US_MR_LOOP;
+
+	if (!ausd) {
+		ausd = kzalloc(sizeof(*ausd), GFP_KERNEL);
+		if (!ausd)
+			return -ENOMEM;
+
+		spi->controller_state = ausd;
+	}
+
+	*ausd = mr;
+
+	dev_dbg(&spi->dev,
+		"setup: bpw %u mode 0x%x -> mr %d %08x\n",
+		bits, spi->mode, spi->chip_select, mr);
+
+	return 0;
+}
+
+static int at91_usart_spi_transfer_one(struct spi_controller *ctlr,
+				       struct spi_device *spi,
+				       struct spi_transfer *xfer)
+{
+	struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
+
+	at91_usart_spi_set_xfer_speed(aus, xfer);
+	aus->xfer_failed = false;
+	aus->current_transfer = xfer;
+	aus->current_tx_remaining_bytes = xfer->len;
+	aus->current_rx_remaining_bytes = xfer->len;
+
+	while ((aus->current_tx_remaining_bytes ||
+		aus->current_rx_remaining_bytes) && !aus->xfer_failed) {
+		at91_usart_spi_read_status(aus);
+		at91_usart_spi_tx(aus);
+		cpu_relax();
+	}
+
+	if (aus->xfer_failed) {
+		dev_err(aus->dev, "Overrun!\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int at91_usart_spi_prepare_message(struct spi_controller *ctlr,
+					  struct spi_message *message)
+{
+	struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
+	struct spi_device *spi = message->spi;
+	u32 *ausd = spi->controller_state;
+
+	at91_usart_spi_writel(aus, CR, US_ENABLE);
+	at91_usart_spi_writel(aus, IER, US_OVRE_RXRDY_IRQS);
+	at91_usart_spi_writel(aus, MR, *ausd);
+
+	return 0;
+}
+
+static int at91_usart_spi_unprepare_message(struct spi_controller *ctlr,
+					    struct spi_message *message)
+{
+	struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
+
+	at91_usart_spi_writel(aus, CR, US_RESET | US_DISABLE);
+	at91_usart_spi_writel(aus, IDR, US_OVRE_RXRDY_IRQS);
+
+	return 0;
+}
+
+static void at91_usart_spi_cleanup(struct spi_device *spi)
+{
+	struct at91_usart_spi_device *ausd = spi->controller_state;
+
+	spi->controller_state = NULL;
+	kfree(ausd);
+}
+
+static void at91_usart_spi_init(struct at91_usart_spi *aus)
+{
+	at91_usart_spi_writel(aus, MR, US_INIT);
+	at91_usart_spi_writel(aus, CR, US_RESET | US_DISABLE);
+}
+
+static int at91_usart_gpio_setup(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.parent->of_node;
+	int i;
+	int ret;
+	int nb;
+
+	if (!np)
+		return -EINVAL;
+
+	nb = of_gpio_named_count(np, "cs-gpios");
+	for (i = 0; i < nb; i++) {
+		int cs_gpio = of_get_named_gpio(np, "cs-gpios", i);
+
+		if (cs_gpio < 0)
+			return cs_gpio;
+
+		if (gpio_is_valid(cs_gpio)) {
+			ret = devm_gpio_request_one(&pdev->dev, cs_gpio,
+						    GPIOF_DIR_OUT,
+						    dev_name(&pdev->dev));
+			if (ret)
+				return ret;
+		}
+	}
+
+	return 0;
+}
+
+static int at91_usart_spi_probe(struct platform_device *pdev)
+{
+	struct resource *regs;
+	struct spi_controller *controller;
+	struct at91_usart_spi *aus;
+	struct clk *clk;
+	int irq;
+	int ret;
+
+	regs = platform_get_resource(to_platform_device(pdev->dev.parent),
+				     IORESOURCE_MEM, 0);
+	if (!regs)
+		return -EINVAL;
+
+	irq = platform_get_irq(to_platform_device(pdev->dev.parent), 0);
+	if (irq < 0)
+		return irq;
+
+	clk = devm_clk_get(pdev->dev.parent, "usart");
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	ret = -ENOMEM;
+	controller = spi_alloc_master(&pdev->dev, sizeof(*aus));
+	if (!controller)
+		goto at91_usart_spi_probe_fail;
+
+	ret = at91_usart_gpio_setup(pdev);
+	if (ret)
+		goto at91_usart_spi_probe_fail;
+
+	controller->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP | SPI_CS_HIGH;
+	controller->dev.of_node = pdev->dev.parent->of_node;
+	controller->bits_per_word_mask = SPI_BPW_MASK(8);
+	controller->setup = at91_usart_spi_setup;
+	controller->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX;
+	controller->transfer_one = at91_usart_spi_transfer_one;
+	controller->prepare_message = at91_usart_spi_prepare_message;
+	controller->unprepare_message = at91_usart_spi_unprepare_message;
+	controller->cleanup = at91_usart_spi_cleanup;
+	controller->max_speed_hz = DIV_ROUND_UP(clk_get_rate(clk),
+						US_MIN_CLK_DIV);
+	controller->min_speed_hz = DIV_ROUND_UP(clk_get_rate(clk),
+						US_MAX_CLK_DIV);
+	platform_set_drvdata(pdev, controller);
+
+	aus = spi_master_get_devdata(controller);
+
+	aus->dev = &pdev->dev;
+	aus->regs = devm_ioremap_resource(&pdev->dev, regs);
+	if (IS_ERR(aus->regs)) {
+		ret = PTR_ERR(aus->regs);
+		goto at91_usart_spi_probe_fail;
+	}
+
+	aus->irq = irq;
+	aus->clk = clk;
+
+	ret = devm_request_irq(&pdev->dev, irq, at91_usart_spi_interrupt, 0,
+			       dev_name(&pdev->dev), controller);
+	if (ret)
+		goto at91_usart_spi_probe_fail;
+
+	ret = clk_prepare_enable(clk);
+	if (ret)
+		goto at91_usart_spi_probe_fail;
+
+	aus->spi_clk = clk_get_rate(clk);
+	at91_usart_spi_init(aus);
+
+	spin_lock_init(&aus->lock);
+	ret = devm_spi_register_master(&pdev->dev, controller);
+	if (ret)
+		goto at91_usart_fail_register_master;
+
+	dev_info(&pdev->dev,
+		 "AT91 USART SPI Controller version 0x%x at %pa (irq %d)\n",
+		 at91_usart_spi_readl(aus, VERSION),
+		 &regs->start, irq);
+
+	return 0;
+
+at91_usart_fail_register_master:
+	clk_disable_unprepare(clk);
+at91_usart_spi_probe_fail:
+	spi_master_put(controller);
+	return ret;
+}
+
+static int at91_usart_spi_remove(struct platform_device *pdev)
+{
+	struct spi_controller *ctlr = platform_get_drvdata(pdev);
+	struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
+
+	clk_disable_unprepare(aus->clk);
+
+	return 0;
+}
+
+static const struct of_device_id at91_usart_spi_dt_ids[] = {
+	{ .compatible = "microchip,at91sam9g45-usart-spi"},
+	{ /* sentinel */}
+};
+
+MODULE_DEVICE_TABLE(of, at91_usart_spi_dt_ids);
+
+static struct platform_driver at91_usart_spi_driver = {
+	.driver = {
+		.name = "at91_usart_spi",
+	},
+	.probe = at91_usart_spi_probe,
+	.remove = at91_usart_spi_remove,
+};
+
+module_platform_driver(at91_usart_spi_driver);
+
+MODULE_DESCRIPTION("Microchip AT91 USART SPI Controller driver");
+MODULE_AUTHOR("Radu Pirea <radu.pirea@microchip.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:at91_usart_spi");
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index df8bd0c7b97d..32886c304641 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -118,6 +118,7 @@ config SERIAL_ATMEL
 	depends on ARCH_AT91 || COMPILE_TEST
 	select SERIAL_CORE
 	select SERIAL_MCTRL_GPIO if GPIOLIB
+	select MFD_AT91_USART
 	help
 	  This enables the driver for the on-chip UARTs of the Atmel
 	  AT91 processors.
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 8e4428725848..267d4d1de3f8 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -193,8 +193,7 @@ static struct console atmel_console;
 
 #if defined(CONFIG_OF)
 static const struct of_device_id atmel_serial_dt_ids[] = {
-	{ .compatible = "atmel,at91rm9200-usart" },
-	{ .compatible = "atmel,at91sam9260-usart" },
+	{ .compatible = "atmel,at91rm9200-usart-serial" },
 	{ /* sentinel */ }
 };
 #endif
@@ -915,6 +914,7 @@ static void atmel_tx_dma(struct uart_port *port)
 static int atmel_prepare_tx_dma(struct uart_port *port)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	struct device *mfd_dev = port->dev->parent;
 	dma_cap_mask_t		mask;
 	struct dma_slave_config config;
 	int ret, nent;
@@ -922,7 +922,7 @@ static int atmel_prepare_tx_dma(struct uart_port *port)
 	dma_cap_zero(mask);
 	dma_cap_set(DMA_SLAVE, mask);
 
-	atmel_port->chan_tx = dma_request_slave_channel(port->dev, "tx");
+	atmel_port->chan_tx = dma_request_slave_channel(mfd_dev, "tx");
 	if (atmel_port->chan_tx == NULL)
 		goto chan_err;
 	dev_info(port->dev, "using %s for tx DMA transfers\n",
@@ -1093,6 +1093,7 @@ static void atmel_rx_from_dma(struct uart_port *port)
 static int atmel_prepare_rx_dma(struct uart_port *port)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	struct device *mfd_dev = port->dev->parent;
 	struct dma_async_tx_descriptor *desc;
 	dma_cap_mask_t		mask;
 	struct dma_slave_config config;
@@ -1104,7 +1105,7 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
 	dma_cap_zero(mask);
 	dma_cap_set(DMA_CYCLIC, mask);
 
-	atmel_port->chan_rx = dma_request_slave_channel(port->dev, "rx");
+	atmel_port->chan_rx = dma_request_slave_channel(mfd_dev, "rx");
 	if (atmel_port->chan_rx == NULL)
 		goto chan_err;
 	dev_info(port->dev, "using %s for rx DMA transfers\n",
@@ -2222,8 +2223,8 @@ static const char *atmel_type(struct uart_port *port)
  */
 static void atmel_release_port(struct uart_port *port)
 {
-	struct platform_device *pdev = to_platform_device(port->dev);
-	int size = pdev->resource[0].end - pdev->resource[0].start + 1;
+	struct platform_device *mpdev = to_platform_device(port->dev->parent);
+	int size = resource_size(mpdev->resource);
 
 	release_mem_region(port->mapbase, size);
 
@@ -2238,8 +2239,8 @@ static void atmel_release_port(struct uart_port *port)
  */
 static int atmel_request_port(struct uart_port *port)
 {
-	struct platform_device *pdev = to_platform_device(port->dev);
-	int size = pdev->resource[0].end - pdev->resource[0].start + 1;
+	struct platform_device *mpdev = to_platform_device(port->dev->parent);
+	int size = resource_size(mpdev->resource);
 
 	if (!request_mem_region(port->mapbase, size, "atmel_serial"))
 		return -EBUSY;
@@ -2341,27 +2342,28 @@ static int atmel_init_port(struct atmel_uart_port *atmel_port,
 {
 	int ret;
 	struct uart_port *port = &atmel_port->uart;
+	struct platform_device *mpdev = to_platform_device(pdev->dev.parent);
 
 	atmel_init_property(atmel_port, pdev);
 	atmel_set_ops(port);
 
-	uart_get_rs485_mode(&pdev->dev, &port->rs485);
+	uart_get_rs485_mode(&mpdev->dev, &port->rs485);
 
 	port->iotype		= UPIO_MEM;
 	port->flags		= UPF_BOOT_AUTOCONF | UPF_IOREMAP;
 	port->ops		= &atmel_pops;
 	port->fifosize		= 1;
 	port->dev		= &pdev->dev;
-	port->mapbase	= pdev->resource[0].start;
-	port->irq	= pdev->resource[1].start;
+	port->mapbase		= mpdev->resource[0].start;
+	port->irq		= mpdev->resource[1].start;
 	port->rs485_config	= atmel_config_rs485;
-	port->membase	= NULL;
+	port->membase		= NULL;
 
 	memset(&atmel_port->rx_ring, 0, sizeof(atmel_port->rx_ring));
 
 	/* for console, the clock could already be configured */
 	if (!atmel_port->clk) {
-		atmel_port->clk = clk_get(&pdev->dev, "usart");
+		atmel_port->clk = clk_get(&mpdev->dev, "usart");
 		if (IS_ERR(atmel_port->clk)) {
 			ret = PTR_ERR(atmel_port->clk);
 			atmel_port->clk = NULL;
@@ -2694,13 +2696,22 @@ static void atmel_serial_probe_fifos(struct atmel_uart_port *atmel_port,
 static int atmel_serial_probe(struct platform_device *pdev)
 {
 	struct atmel_uart_port *atmel_port;
-	struct device_node *np = pdev->dev.of_node;
+	struct device_node *np = pdev->dev.parent->of_node;
 	void *data;
 	int ret = -ENODEV;
 	bool rs485_enabled;
 
 	BUILD_BUG_ON(ATMEL_SERIAL_RINGSIZE & (ATMEL_SERIAL_RINGSIZE - 1));
 
+	/*
+	 * In device tree there is no node with "atmel,at91rm9200-usart-serial"
+	 * as compatible string. This driver is probed by at91-usart mfd driver
+	 * which is just a wrapper over the atmel_serial driver and
+	 * spi-at91-usart driver. All attributes needed by this driver are
+	 * found in of_node of parent.
+	 */
+	pdev->dev.of_node = np;
+
 	ret = of_alias_get_id(np, "serial");
 	if (ret < 0)
 		/* port id not found in platform data nor device-tree aliases:
@@ -2836,6 +2847,7 @@ static int atmel_serial_remove(struct platform_device *pdev)
 
 	clk_put(atmel_port->clk);
 	atmel_port->clk = NULL;
+	pdev->dev.of_node = NULL;
 
 	return ret;
 }
@@ -2846,7 +2858,7 @@ static struct platform_driver atmel_serial_driver = {
 	.suspend	= atmel_serial_suspend,
 	.resume		= atmel_serial_resume,
 	.driver		= {
-		.name			= "atmel_usart",
+		.name			= "atmel_usart_serial",
 		.of_match_table		= of_match_ptr(atmel_serial_dt_ids),
 	},
 };