[PATCH 0/2] spi: Add Meson SPICC driver

[PATCH 0/2] spi: Add Meson SPICC driver

[Neil Armstrong]

The Meson SPICC is generic SPI controller for general purpose Full-Duplex
communications with dedicated 16 words RX/TX PIO FIFOs.
It differs completely from the SPIFC, and thus need a separate driver.

The current driver only supportd the PIO transfer mode since the DMA seems
broken on available hardware.

This driver has been tested on a Amlogic S905X board.

Neil Armstrong (2):
  dt-bindings: spi-meson: Add SPICC bindings
  spi: Add Meson SPICC driver

 .../devicetree/bindings/spi/spi-meson.txt          |  31 ++
 drivers/spi/Kconfig                                |   7 +
 drivers/spi/Makefile                               |   1 +
 drivers/spi/spi-meson-spicc.c                      | 619 +++++++++++++++++++++
 4 files changed, 658 insertions(+)
 create mode 100644 drivers/spi/spi-meson-spicc.c

-- 
1.9.1

[PATCH 1/2] dt-bindings: spi-meson: Add SPICC bindings

[Neil Armstrong]

Add the SPICC (SPI Communications Controller) bindings variant.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
---
 .../devicetree/bindings/spi/spi-meson.txt          | 31 ++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/spi-meson.txt b/Documentation/devicetree/bindings/spi/spi-meson.txt
index dc6d031..825c39c 100644
--- a/Documentation/devicetree/bindings/spi/spi-meson.txt
+++ b/Documentation/devicetree/bindings/spi/spi-meson.txt
@@ -20,3 +20,34 @@ Required properties:
 		#address-cells = <1>;
 		#size-cells = <0>;
 	};
+
+* SPICC (SPI Communication Controller)
+
+The Meson SPICC is generic SPI controller for general purpose Full-Duplex
+communications with dedicated 16 words RX/TX PIO FIFOs.
+
+Required properties:
+ - compatible: should be "amlogic,meson-gx-spicc" on Amlogic GX SoCs.
+ - reg: physical base address and length of the controller registers
+ - interrupts: The interrupt specifier
+ - clock-names: Must contain "core"
+ - clocks: phandle of the input clock for the baud rate generator
+ - #address-cells: should be 1
+ - #size-cells: should be 0
+
+Optional properties:
+ - resets: phandle of the internal reset line
+
+See ../spi/spi-bus.txt for more details on SPI bus master and slave devices
+required and optional properties.
+
+Example :
+	spi@c1108d80 {
+		compatible = "amlogic,meson-gx-spicc";
+		reg = <0xc1108d80 0x80>;
+		interrupts = <GIC_SPI 112 IRQ_TYPE_LEVEL_HIGH>;
+		clock-names = "core";
+		clocks = <&clk81>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+	};
-- 
1.9.1

Re: [PATCH 1/2] dt-bindings: spi-meson: Add SPICC bindings

[Mark Brown]

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On Tue, May 23, 2017 at 03:39:32PM +0200, Neil Armstrong wrote:
> Add the SPICC (SPI Communications Controller) bindings variant.

Please submit patches using subject lines reflecting the style for the
subsystem.  This makes it easier for people to identify relevant
patches.  Look at what existing commits in the area you're changing are
doing and make sure your subject lines visually resemble what they're
doing.

[-- Attachment #2: signature.asc --]
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Applied "spi: meson: Add SPICC bindings" to the spi tree

[Mark Brown]

The patch

   spi: meson: Add SPICC bindings

has been applied to the spi tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 01a330da0c0ea2971be039f74a2288cbd2d17fbf Mon Sep 17 00:00:00 2001
From: Neil Armstrong <narmstrong@baylibre.com>
Date: Tue, 23 May 2017 15:39:32 +0200
Subject: [PATCH] spi: meson: Add SPICC bindings

Add the SPICC (SPI Communications Controller) bindings variant.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 .../devicetree/bindings/spi/spi-meson.txt          | 31 ++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/spi-meson.txt b/Documentation/devicetree/bindings/spi/spi-meson.txt
index dc6d0313324a..825c39cae74a 100644
--- a/Documentation/devicetree/bindings/spi/spi-meson.txt
+++ b/Documentation/devicetree/bindings/spi/spi-meson.txt
@@ -20,3 +20,34 @@ Required properties:
 		#address-cells = <1>;
 		#size-cells = <0>;
 	};
+
+* SPICC (SPI Communication Controller)
+
+The Meson SPICC is generic SPI controller for general purpose Full-Duplex
+communications with dedicated 16 words RX/TX PIO FIFOs.
+
+Required properties:
+ - compatible: should be "amlogic,meson-gx-spicc" on Amlogic GX SoCs.
+ - reg: physical base address and length of the controller registers
+ - interrupts: The interrupt specifier
+ - clock-names: Must contain "core"
+ - clocks: phandle of the input clock for the baud rate generator
+ - #address-cells: should be 1
+ - #size-cells: should be 0
+
+Optional properties:
+ - resets: phandle of the internal reset line
+
+See ../spi/spi-bus.txt for more details on SPI bus master and slave devices
+required and optional properties.
+
+Example :
+	spi@c1108d80 {
+		compatible = "amlogic,meson-gx-spicc";
+		reg = <0xc1108d80 0x80>;
+		interrupts = <GIC_SPI 112 IRQ_TYPE_LEVEL_HIGH>;
+		clock-names = "core";
+		clocks = <&clk81>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+	};
-- 
2.11.0

[PATCH 2/2] spi: Add Meson SPICC driver

[Neil Armstrong]

The SPICC hardware block on the Amlogic SoCs is Communication oriented and
can do Full-Duplex 8- to 32-bit width SPI transfers up to 30MHz.

The current driver only supportd the PIO transfer mode since the DMA seems
broken on available hardware.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
---
 drivers/spi/Kconfig           |   7 +
 drivers/spi/Makefile          |   1 +
 drivers/spi/spi-meson-spicc.c | 619 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 627 insertions(+)
 create mode 100644 drivers/spi/spi-meson-spicc.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 1761c90..1dcb14c 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -393,6 +393,13 @@ config SPI_FSL_ESPI
 	  From MPC8536, 85xx platform uses the controller, and all P10xx,
 	  P20xx, P30xx,P40xx, P50xx uses this controller.
 
+config SPI_MESON_SPICC
+	tristate "Amlogic Meson SPICC controller"
+	depends on ARCH_MESON || COMPILE_TEST
+	help
+	  This enables master mode support for the SPICC (SPI communication
+	  controller) available in Amlogic Meson SoCs.
+
 config SPI_MESON_SPIFC
 	tristate "Amlogic Meson SPIFC controller"
 	depends on ARCH_MESON || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index b375a7a..0d8c95e 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -53,6 +53,7 @@ obj-$(CONFIG_SPI_LANTIQ_SSC)		+= spi-lantiq-ssc.o
 obj-$(CONFIG_SPI_JCORE)			+= spi-jcore.o
 obj-$(CONFIG_SPI_LM70_LLP)		+= spi-lm70llp.o
 obj-$(CONFIG_SPI_LP8841_RTC)		+= spi-lp8841-rtc.o
+obj-$(CONFIG_SPI_MESON_SPICC)		+= spi-meson-spicc.o
 obj-$(CONFIG_SPI_MESON_SPIFC)		+= spi-meson-spifc.o
 obj-$(CONFIG_SPI_MPC512x_PSC)		+= spi-mpc512x-psc.o
 obj-$(CONFIG_SPI_MPC52xx_PSC)		+= spi-mpc52xx-psc.o
diff --git a/drivers/spi/spi-meson-spicc.c b/drivers/spi/spi-meson-spicc.c
new file mode 100644
index 0000000..7f84296
--- /dev/null
+++ b/drivers/spi/spi-meson-spicc.c
@@ -0,0 +1,619 @@
+/*
+ * Driver for Amlogic Meson SPI communication controller (SPICC)
+ *
+ * Copyright (C) BayLibre, SAS
+ * Author: Neil Armstrong <narmstrong@baylibre.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/types.h>
+#include <linux/interrupt.h>
+#include <linux/reset.h>
+#include <linux/gpio.h>
+
+/*
+ * The Meson SPICC controller could support DMA based transfers, but is not
+ * implemented by the vendor code, and while having the registers documentation
+ * it has never worked on the GXL Hardware.
+ * The PIO mode is the only mode implemented, and due to badly designed HW :
+ * - all transfers are cutted in 16 words burst because the FIFO hangs on
+ *   TX underflow, and there is no TX "Half-Empty" interrupt, so we go by
+ *   FIFO max size chunk only
+ * - CS management is dumb, and goes UP between every burst, so is really a
+ *   "Data Valid" signal than a Chip Select, GPIO link should be used instead
+ *   to have a CS go down over the full transfer
+ */
+
+#define SPICC_MAX_FREQ	30000000
+#define SPICC_MAX_BURST	128
+
+/* Register Map */
+#define SPICC_RXDATA	0x00
+
+#define SPICC_TXDATA	0x04
+
+#define SPICC_CONREG	0x08
+#define SPICC_ENABLE		BIT(0)
+#define SPICC_MODE_MASTER	BIT(1)
+#define SPICC_XCH		BIT(2)
+#define SPICC_SMC		BIT(3)
+#define SPICC_POL		BIT(4)
+#define SPICC_PHA		BIT(5)
+#define SPICC_SSCTL		BIT(6)
+#define SPICC_SSPOL		BIT(7)
+#define SPICC_DRCTL_MASK	GENMASK(9, 8)
+#define SPICC_DRCTL_IGNORE	0
+#define SPICC_DRCTL_FALLING	1
+#define SPICC_DRCTL_LOWLEVEL	2
+#define SPICC_CS_MASK		GENMASK(13, 12)
+#define SPICC_DATARATE_MASK	GENMASK(18, 16)
+#define SPICC_DATARATE_DIV4	0
+#define SPICC_DATARATE_DIV8	1
+#define SPICC_DATARATE_DIV16	2
+#define SPICC_DATARATE_DIV32	3
+#define SPICC_BITLENGTH_MASK	GENMASK(24, 19)
+#define SPICC_BURSTLENGTH_MASK	GENMASK(31, 25)
+
+#define SPICC_INTREG	0x0c
+#define SPICC_TE_EN	BIT(0) /* TX FIFO Empty Interrupt */
+#define SPICC_TH_EN	BIT(1) /* TX FIFO Half-Full Interrupt */
+#define SPICC_TF_EN	BIT(2) /* TX FIFO Full Interrupt */
+#define SPICC_RR_EN	BIT(3) /* RX FIFO Ready Interrupt */
+#define SPICC_RH_EN	BIT(4) /* RX FIFO Half-Full Interrupt */
+#define SPICC_RF_EN	BIT(5) /* RX FIFO Full Interrupt */
+#define SPICC_RO_EN	BIT(6) /* RX FIFO Overflow Interrupt */
+#define SPICC_TC_EN	BIT(7) /* Transfert Complete Interrupt */
+
+#define SPICC_DMAREG	0x10
+#define SPICC_DMA_ENABLE		BIT(0)
+#define SPICC_TXFIFO_THRESHOLD_MASK	GENMASK(5, 1)
+#define SPICC_RXFIFO_THRESHOLD_MASK	GENMASK(10, 6)
+#define SPICC_READ_BURST_MASK		GENMASK(14, 11)
+#define SPICC_WRITE_BURST_MASK		GENMASK(18, 15)
+#define SPICC_DMA_URGENT		BIT(19)
+#define SPICC_DMA_THREADID_MASK		GENMASK(25, 20)
+#define SPICC_DMA_BURSTNUM_MASK		GENMASK(31, 26)
+
+#define SPICC_STATREG	0x14
+#define SPICC_TE	BIT(0) /* TX FIFO Empty Interrupt */
+#define SPICC_TH	BIT(1) /* TX FIFO Half-Full Interrupt */
+#define SPICC_TF	BIT(2) /* TX FIFO Full Interrupt */
+#define SPICC_RR	BIT(3) /* RX FIFO Ready Interrupt */
+#define SPICC_RH	BIT(4) /* RX FIFO Half-Full Interrupt */
+#define SPICC_RF	BIT(5) /* RX FIFO Full Interrupt */
+#define SPICC_RO	BIT(6) /* RX FIFO Overflow Interrupt */
+#define SPICC_TC	BIT(7) /* Transfert Complete Interrupt */
+
+#define SPICC_PERIODREG	0x18
+#define SPICC_PERIOD	GENMASK(14, 0)	/* Wait cycles */
+
+#define SPICC_TESTREG	0x1c
+#define SPICC_TXCNT_MASK	GENMASK(4, 0)	/* TX FIFO Counter */
+#define SPICC_RXCNT_MASK	GENMASK(9, 5)	/* RX FIFO Counter */
+#define SPICC_SMSTATUS_MASK	GENMASK(12, 10)	/* State Machine Status */
+#define SPICC_LBC_RO		BIT(13)	/* Loop Back Control Read-Only */
+#define SPICC_LBC_W1		BIT(14) /* Loop Back Control Write-Only */
+#define SPICC_SWAP_RO		BIT(14) /* RX FIFO Data Swap Read-Only */
+#define SPICC_SWAP_W1		BIT(15) /* RX FIFO Data Swap Write-Only */
+#define SPICC_DLYCTL_RO_MASK	GENMASK(20, 15) /* Delay Control Read-Only */
+#define SPICC_DLYCTL_W1_MASK	GENMASK(21, 16) /* Delay Control Write-Only */
+#define SPICC_FIFORST_RO_MASK	GENMASK(22, 21) /* FIFO Softreset Read-Only */
+#define SPICC_FIFORST_W1_MASK	GENMASK(23, 22) /* FIFO Softreset Write-Only */
+
+#define SPICC_DRADDR	0x20	/* Read Address of DMA */
+
+#define SPICC_DWADDR	0x24	/* Write Address of DMA */
+
+#define writel_bits_relaxed(mask, val, addr) \
+	writel_relaxed((readl_relaxed(addr) & ~(mask)) | (val), addr)
+
+#define SPICC_BURST_MAX	16
+#define SPICC_FIFO_HALF 10
+
+struct meson_spicc_device {
+	struct spi_master		*master;
+	struct platform_device		*pdev;
+	void __iomem			*base;
+	struct clk			*core;
+	struct spi_message		*message;
+	struct spi_transfer		*xfer;
+	u8				*tx_buf;
+	u8				*rx_buf;
+	unsigned int			bytes_per_word;
+	unsigned long			tx_remain;
+	unsigned long			txb_remain;
+	unsigned long			rx_remain;
+	unsigned long			rxb_remain;
+	unsigned long			xfer_remain;
+	bool				is_burst_end;
+	bool				is_last_burst;
+};
+
+static inline bool meson_spicc_txfull(struct meson_spicc_device *spicc)
+{
+	return !!FIELD_GET(SPICC_TF,
+			   readl_relaxed(spicc->base + SPICC_STATREG));
+}
+
+static inline bool meson_spicc_rxready(struct meson_spicc_device *spicc)
+{
+	return FIELD_GET(SPICC_RH | SPICC_RR | SPICC_RF_EN,
+			 readl_relaxed(spicc->base + SPICC_STATREG));
+}
+
+static inline u32 meson_spicc_pull_data(struct meson_spicc_device *spicc)
+{
+	unsigned int bytes = spicc->bytes_per_word;
+	unsigned int byte_shift = 0;
+	u32 data = 0;
+	u8 byte;
+
+	while (bytes--) {
+		byte = *spicc->tx_buf++;
+		data |= (byte & 0xff) << byte_shift;
+		byte_shift += 8;
+	}
+
+	spicc->tx_remain--;
+	return data;
+}
+
+static inline void meson_spicc_push_data(struct meson_spicc_device *spicc,
+					 u32 data)
+{
+	unsigned int bytes = spicc->bytes_per_word;
+	unsigned int byte_shift = 0;
+	u8 byte;
+
+	while (bytes--) {
+		byte = (data >> byte_shift) & 0xff;
+		*spicc->rx_buf++ = byte;
+		byte_shift += 8;
+	}
+
+	spicc->rx_remain--;
+}
+
+static inline void meson_spicc_rx(struct meson_spicc_device *spicc)
+{
+	/* Empty RX FIFO */
+	while (spicc->rx_remain &&
+	       meson_spicc_rxready(spicc))
+		meson_spicc_push_data(spicc,
+				readl_relaxed(spicc->base + SPICC_RXDATA));
+}
+
+static inline void meson_spicc_tx(struct meson_spicc_device *spicc)
+{
+	/* Fill Up TX FIFO */
+	while (spicc->tx_remain &&
+	       !meson_spicc_txfull(spicc))
+		writel_relaxed(meson_spicc_pull_data(spicc),
+			       spicc->base + SPICC_TXDATA);
+}
+
+static inline u32 meson_spicc_setup_rx_irq(struct meson_spicc_device *spicc,
+					   u32 irq_ctrl)
+{
+	if (spicc->rx_remain > SPICC_FIFO_HALF)
+		irq_ctrl |= SPICC_RH_EN;
+	else
+		irq_ctrl |= SPICC_RR_EN;
+
+	return irq_ctrl;
+}
+
+static inline void meson_spicc_setup_burst(struct meson_spicc_device *spicc,
+					   unsigned int burst_len)
+{
+	/* Setup Xfer variables */
+	spicc->tx_remain = burst_len;
+	spicc->rx_remain = burst_len;
+	spicc->xfer_remain -= burst_len * spicc->bytes_per_word;
+	spicc->is_burst_end = false;
+	if (burst_len < SPICC_BURST_MAX || !spicc->xfer_remain)
+		spicc->is_last_burst = true;
+	else
+		spicc->is_last_burst = false;
+
+	/* Setup burst length */
+	writel_bits_relaxed(SPICC_BURSTLENGTH_MASK,
+			FIELD_PREP(SPICC_BURSTLENGTH_MASK,
+				burst_len),
+			spicc->base + SPICC_CONREG);
+
+	/* Fill TX FIFO */
+	meson_spicc_tx(spicc);
+}
+
+static irqreturn_t meson_spicc_irq(int irq, void *data)
+{
+	struct meson_spicc_device *spicc = (void *) data;
+	u32 ctrl = readl_relaxed(spicc->base + SPICC_INTREG);
+	u32 stat = readl_relaxed(spicc->base + SPICC_STATREG) & ctrl;
+
+	ctrl &= ~(SPICC_RH_EN | SPICC_RR_EN);
+
+	/* Empty RX FIFO */
+	meson_spicc_rx(spicc);
+
+	/* Enable TC interrupt since we transferred everything */
+	if (!spicc->tx_remain && !spicc->rx_remain) {
+		spicc->is_burst_end = true;
+
+		/* Enable TC interrupt */
+		ctrl |= SPICC_TC_EN;
+
+		/* Reload IRQ status */
+		stat = readl_relaxed(spicc->base + SPICC_STATREG) & ctrl;
+	}
+
+	/* Check transfer complete */
+	if ((stat & SPICC_TC) && spicc->is_burst_end) {
+		unsigned int burst_len;
+
+		/* Clear TC bit */
+		writel_relaxed(SPICC_TC, spicc->base + SPICC_STATREG);
+
+		/* Disable TC interrupt */
+		ctrl &= ~SPICC_TC_EN;
+
+		if (spicc->is_last_burst) {
+			/* Disable all IRQs */
+			writel(0, spicc->base + SPICC_INTREG);
+
+			spi_finalize_current_transfer(spicc->master);
+
+			return IRQ_HANDLED;
+		}
+
+		burst_len = min_t(unsigned int,
+				  spicc->xfer_remain / spicc->bytes_per_word,
+				  SPICC_BURST_MAX);
+
+		/* Setup burst */
+		meson_spicc_setup_burst(spicc, burst_len);
+
+		/* Restart burst */
+		writel_bits_relaxed(SPICC_XCH, SPICC_XCH,
+				    spicc->base + SPICC_CONREG);
+	}
+
+	/* Setup RX interrupt trigger */
+	ctrl = meson_spicc_setup_rx_irq(spicc, ctrl);
+
+	/* Reconfigure interrupts */
+	writel(ctrl, spicc->base + SPICC_INTREG);
+
+	return IRQ_HANDLED;
+}
+
+static u32 meson_spicc_setup_speed(struct meson_spicc_device *spicc, u32 conf,
+				   u32 speed)
+{
+	unsigned long parent, value;
+	unsigned int i, div;
+
+	parent = clk_get_rate(spicc->core);
+
+	/* Find closest inferior/equal possible speed */
+	for (i = 0 ; i < 7 ; ++i) {
+		/* 2^(data_rate+2) */
+		value = parent >> (i + 2);
+
+		if (value <= speed)
+			break;
+	}
+
+	/* If provided speed it lower than max divider, use max divider */
+	if (i > 7) {
+		div = 7;
+		dev_warn_once(&spicc->pdev->dev, "unable to get close to speed %u\n",
+			      speed);
+	} else
+		div = i;
+
+	dev_dbg(&spicc->pdev->dev, "parent %lu, speed %u -> %lu (%u)\n",
+		parent, speed, value, div);
+
+	conf &= ~SPICC_DATARATE_MASK;
+	conf |= FIELD_PREP(SPICC_DATARATE_MASK, div);
+
+	return conf;
+}
+
+static void meson_spicc_setup_xfer(struct meson_spicc_device *spicc,
+				   struct spi_transfer *xfer)
+{
+	u32 conf, conf_orig;
+
+	/* Read original configuration */
+	conf = conf_orig = readl_relaxed(spicc->base + SPICC_CONREG);
+
+	/* Select closest divider */
+	conf = meson_spicc_setup_speed(spicc, conf, xfer->speed_hz);
+
+	/* Setup word width */
+	conf &= ~SPICC_BITLENGTH_MASK;
+	conf |= FIELD_PREP(SPICC_BITLENGTH_MASK,
+			   (spicc->bytes_per_word << 3) - 1);
+
+	/* Ignore if unchanged */
+	if (conf != conf_orig)
+		writel_relaxed(conf, spicc->base + SPICC_CONREG);
+}
+
+static int meson_spicc_transfer_one(struct spi_master *master,
+				    struct spi_device *spi,
+				    struct spi_transfer *xfer)
+{
+	struct meson_spicc_device *spicc = spi_master_get_devdata(master);
+	unsigned int burst_len;
+	u32 irq = 0;
+
+	/* Store current transfer */
+	spicc->xfer = xfer;
+
+	/* Setup transfer parameters */
+	spicc->tx_buf = (u8 *)xfer->tx_buf;
+	spicc->rx_buf = (u8 *)xfer->rx_buf;
+	spicc->xfer_remain = xfer->len;
+
+	/* Pre-calculate word size */
+	spicc->bytes_per_word =
+	   DIV_ROUND_UP(spicc->xfer->bits_per_word, 8);
+
+	/* Setup transfer parameters */
+	meson_spicc_setup_xfer(spicc, xfer);
+
+	burst_len = min_t(unsigned int,
+			  spicc->xfer_remain / spicc->bytes_per_word,
+			  SPICC_BURST_MAX);
+
+	meson_spicc_setup_burst(spicc, burst_len);
+
+	irq = meson_spicc_setup_rx_irq(spicc, irq);
+
+	/* Start burst */
+	writel_bits_relaxed(SPICC_XCH, SPICC_XCH, spicc->base + SPICC_CONREG);
+
+	/* Enable interrupts */
+	writel_relaxed(irq, spicc->base + SPICC_INTREG);
+
+	return 1;
+}
+
+static int meson_spicc_prepare_message(struct spi_master *master,
+				       struct spi_message *message)
+{
+	struct meson_spicc_device *spicc = spi_master_get_devdata(master);
+	struct spi_device *spi = message->spi;
+	u32 conf = 0;
+
+	/* Store current message */
+	spicc->message = message;
+
+	/* Enable Master */
+	conf |= SPICC_ENABLE;
+	conf |= SPICC_MODE_MASTER;
+
+	/* SMC = 0 */
+
+	/* Setup transfer mode */
+	if (spi->mode & SPI_CPOL)
+		conf |= SPICC_POL;
+	else
+		conf &= ~SPICC_POL;
+
+	if (spi->mode & SPI_CPHA)
+		conf |= SPICC_PHA;
+	else
+		conf &= ~SPICC_PHA;
+
+	/* SSCTL = 0 */
+
+	if (spi->mode & SPI_CS_HIGH)
+		conf |= SPICC_SSPOL;
+	else
+		conf &= ~SPICC_SSPOL;
+
+	if (spi->mode & SPI_READY)
+		conf |= FIELD_PREP(SPICC_DRCTL_MASK, SPICC_DRCTL_LOWLEVEL);
+	else
+		conf |= FIELD_PREP(SPICC_DRCTL_MASK, SPICC_DRCTL_IGNORE);
+
+	/* Select CS */
+	conf |= FIELD_PREP(SPICC_CS_MASK, spi->chip_select);
+
+	/* Default Clock rate core/4 */
+
+	/* Default 8bit word */
+	conf |= FIELD_PREP(SPICC_BITLENGTH_MASK, 8 - 1);
+
+	writel_relaxed(conf, spicc->base + SPICC_CONREG);
+
+	/* Setup no wait cycles by default */
+	writel_relaxed(0, spicc->base + SPICC_PERIODREG);
+
+	writel_bits_relaxed(BIT(24), BIT(24), spicc->base + SPICC_TESTREG);
+
+	return 0;
+}
+
+static int meson_spicc_unprepare_transfer(struct spi_master *master)
+{
+	struct meson_spicc_device *spicc = spi_master_get_devdata(master);
+
+	/* Disable all IRQs */
+	writel(0, spicc->base + SPICC_INTREG);
+
+	/* Disable controller */
+	writel_bits_relaxed(SPICC_ENABLE, 0, spicc->base + SPICC_CONREG);
+
+	device_reset_optional(&spicc->pdev->dev);
+
+	return 0;
+}
+
+static int meson_spicc_setup(struct spi_device *spi)
+{
+	int ret = 0;
+
+	if (!spi->controller_state)
+		spi->controller_state = spi_master_get_devdata(spi->master);
+	else if (gpio_is_valid(spi->cs_gpio))
+		goto out_gpio;
+	else if (spi->cs_gpio == -ENOENT)
+		return 0;
+
+	if (gpio_is_valid(spi->cs_gpio)) {
+		ret = gpio_request(spi->cs_gpio, dev_name(&spi->dev));
+		if (ret) {
+			dev_err(&spi->dev, "failed to request cs gpio\n");
+			return ret;
+		}
+	}
+
+out_gpio:
+	ret = gpio_direction_output(spi->cs_gpio,
+			!(spi->mode & SPI_CS_HIGH));
+
+	return ret;
+}
+
+static void meson_spicc_cleanup(struct spi_device *spi)
+{
+	if (gpio_is_valid(spi->cs_gpio))
+		gpio_free(spi->cs_gpio);
+
+	spi->controller_state = NULL;
+}
+
+static int meson_spicc_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct meson_spicc_device *spicc;
+	struct resource *res;
+	int ret, irq, rate;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(*spicc));
+	if (!master) {
+		dev_err(&pdev->dev, "master allocation failed\n");
+		return -ENOMEM;
+	}
+	spicc = spi_master_get_devdata(master);
+	spicc->master = master;
+
+	spicc->pdev = pdev;
+	platform_set_drvdata(pdev, spicc);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	spicc->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(spicc->base)) {
+		dev_err(&pdev->dev, "io resource mapping failed\n");
+		ret = PTR_ERR(spicc->base);
+		goto out_master;
+	}
+
+	/* Disable all IRQs */
+	writel_relaxed(0, spicc->base + SPICC_INTREG);
+
+	irq = platform_get_irq(pdev, 0);
+	ret = devm_request_irq(&pdev->dev, irq, meson_spicc_irq,
+			       0, NULL, spicc);
+	if (ret) {
+		dev_err(&pdev->dev, "irq request failed\n");
+		goto out_master;
+	}
+
+	spicc->core = devm_clk_get(&pdev->dev, "core");
+	if (IS_ERR(spicc->core)) {
+		dev_err(&pdev->dev, "core clock request failed\n");
+		ret = PTR_ERR(spicc->core);
+		goto out_master;
+	}
+
+	ret = clk_prepare_enable(spicc->core);
+	if (ret) {
+		dev_err(&pdev->dev, "core clock enable failed\n");
+		goto out_master;
+	}
+	rate = clk_get_rate(spicc->core);
+
+	device_reset_optional(&pdev->dev);
+
+	master->num_chipselect = 4;
+	master->dev.of_node = pdev->dev.of_node;
+	master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_CS_HIGH;
+	master->bits_per_word_mask = SPI_BPW_MASK(32) |
+				     SPI_BPW_MASK(24) |
+				     SPI_BPW_MASK(16) |
+				     SPI_BPW_MASK(8);
+	master->flags = (SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX);
+	master->min_speed_hz = rate >> 9;
+	master->setup = meson_spicc_setup;
+	master->cleanup = meson_spicc_cleanup;
+	master->prepare_message = meson_spicc_prepare_message;
+	master->unprepare_transfer_hardware = meson_spicc_unprepare_transfer;
+	master->transfer_one = meson_spicc_transfer_one;
+
+	/* Setup max rate according to the Meson GX datasheet */
+	if ((rate >> 2) > SPICC_MAX_FREQ)
+		master->max_speed_hz = SPICC_MAX_FREQ;
+	else
+		master->max_speed_hz = rate >> 2;
+
+	ret = devm_spi_register_master(&pdev->dev, master);
+	if (!ret)
+		return 0;
+
+	dev_err(&pdev->dev, "spi master registration failed\n");
+
+out_master:
+	spi_master_put(master);
+
+	return ret;
+}
+
+static int meson_spicc_remove(struct platform_device *pdev)
+{
+	struct meson_spicc_device *spicc = platform_get_drvdata(pdev);
+
+	/* Disable SPI */
+	writel(0, spicc->base + SPICC_CONREG);
+
+	clk_disable_unprepare(spicc->core);
+
+	return 0;
+}
+
+static const struct of_device_id meson_spicc_of_match[] = {
+	{ .compatible = "amlogic,meson-gx-spicc", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, meson_spicc_of_match);
+
+static struct platform_driver meson_spicc_driver = {
+	.probe   = meson_spicc_probe,
+	.remove  = meson_spicc_remove,
+	.driver  = {
+		.name = "meson-spicc",
+		.of_match_table = of_match_ptr(meson_spicc_of_match),
+	},
+};
+
+module_platform_driver(meson_spicc_driver);
+
+MODULE_DESCRIPTION("Meson SPI Communication Controller driver");
+MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
+MODULE_LICENSE("GPL");
-- 
1.9.1

Applied "spi: Add Meson SPICC driver" to the spi tree

[Mark Brown]

The patch

   spi: Add Meson SPICC driver

has been applied to the spi tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 454fa271bc4e71090ef55087027c3f8701fadc5b Mon Sep 17 00:00:00 2001
From: Neil Armstrong <narmstrong@baylibre.com>
Date: Tue, 23 May 2017 15:39:33 +0200
Subject: [PATCH] spi: Add Meson SPICC driver

The SPICC hardware block on the Amlogic SoCs is Communication oriented and
can do Full-Duplex 8- to 32-bit width SPI transfers up to 30MHz.

The current driver only supportd the PIO transfer mode since the DMA seems
broken on available hardware.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 drivers/spi/Kconfig           |   7 +
 drivers/spi/Makefile          |   1 +
 drivers/spi/spi-meson-spicc.c | 619 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 627 insertions(+)
 create mode 100644 drivers/spi/spi-meson-spicc.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 1761c9004fc1..1dcb14ce6f38 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -393,6 +393,13 @@ config SPI_FSL_ESPI
 	  From MPC8536, 85xx platform uses the controller, and all P10xx,
 	  P20xx, P30xx,P40xx, P50xx uses this controller.
 
+config SPI_MESON_SPICC
+	tristate "Amlogic Meson SPICC controller"
+	depends on ARCH_MESON || COMPILE_TEST
+	help
+	  This enables master mode support for the SPICC (SPI communication
+	  controller) available in Amlogic Meson SoCs.
+
 config SPI_MESON_SPIFC
 	tristate "Amlogic Meson SPIFC controller"
 	depends on ARCH_MESON || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index b375a7a89216..0d8c95e66a9b 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -53,6 +53,7 @@ obj-$(CONFIG_SPI_LANTIQ_SSC)		+= spi-lantiq-ssc.o
 obj-$(CONFIG_SPI_JCORE)			+= spi-jcore.o
 obj-$(CONFIG_SPI_LM70_LLP)		+= spi-lm70llp.o
 obj-$(CONFIG_SPI_LP8841_RTC)		+= spi-lp8841-rtc.o
+obj-$(CONFIG_SPI_MESON_SPICC)		+= spi-meson-spicc.o
 obj-$(CONFIG_SPI_MESON_SPIFC)		+= spi-meson-spifc.o
 obj-$(CONFIG_SPI_MPC512x_PSC)		+= spi-mpc512x-psc.o
 obj-$(CONFIG_SPI_MPC52xx_PSC)		+= spi-mpc52xx-psc.o
diff --git a/drivers/spi/spi-meson-spicc.c b/drivers/spi/spi-meson-spicc.c
new file mode 100644
index 000000000000..7f8429635502
--- /dev/null
+++ b/drivers/spi/spi-meson-spicc.c
@@ -0,0 +1,619 @@
+/*
+ * Driver for Amlogic Meson SPI communication controller (SPICC)
+ *
+ * Copyright (C) BayLibre, SAS
+ * Author: Neil Armstrong <narmstrong@baylibre.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/types.h>
+#include <linux/interrupt.h>
+#include <linux/reset.h>
+#include <linux/gpio.h>
+
+/*
+ * The Meson SPICC controller could support DMA based transfers, but is not
+ * implemented by the vendor code, and while having the registers documentation
+ * it has never worked on the GXL Hardware.
+ * The PIO mode is the only mode implemented, and due to badly designed HW :
+ * - all transfers are cutted in 16 words burst because the FIFO hangs on
+ *   TX underflow, and there is no TX "Half-Empty" interrupt, so we go by
+ *   FIFO max size chunk only
+ * - CS management is dumb, and goes UP between every burst, so is really a
+ *   "Data Valid" signal than a Chip Select, GPIO link should be used instead
+ *   to have a CS go down over the full transfer
+ */
+
+#define SPICC_MAX_FREQ	30000000
+#define SPICC_MAX_BURST	128
+
+/* Register Map */
+#define SPICC_RXDATA	0x00
+
+#define SPICC_TXDATA	0x04
+
+#define SPICC_CONREG	0x08
+#define SPICC_ENABLE		BIT(0)
+#define SPICC_MODE_MASTER	BIT(1)
+#define SPICC_XCH		BIT(2)
+#define SPICC_SMC		BIT(3)
+#define SPICC_POL		BIT(4)
+#define SPICC_PHA		BIT(5)
+#define SPICC_SSCTL		BIT(6)
+#define SPICC_SSPOL		BIT(7)
+#define SPICC_DRCTL_MASK	GENMASK(9, 8)
+#define SPICC_DRCTL_IGNORE	0
+#define SPICC_DRCTL_FALLING	1
+#define SPICC_DRCTL_LOWLEVEL	2
+#define SPICC_CS_MASK		GENMASK(13, 12)
+#define SPICC_DATARATE_MASK	GENMASK(18, 16)
+#define SPICC_DATARATE_DIV4	0
+#define SPICC_DATARATE_DIV8	1
+#define SPICC_DATARATE_DIV16	2
+#define SPICC_DATARATE_DIV32	3
+#define SPICC_BITLENGTH_MASK	GENMASK(24, 19)
+#define SPICC_BURSTLENGTH_MASK	GENMASK(31, 25)
+
+#define SPICC_INTREG	0x0c
+#define SPICC_TE_EN	BIT(0) /* TX FIFO Empty Interrupt */
+#define SPICC_TH_EN	BIT(1) /* TX FIFO Half-Full Interrupt */
+#define SPICC_TF_EN	BIT(2) /* TX FIFO Full Interrupt */
+#define SPICC_RR_EN	BIT(3) /* RX FIFO Ready Interrupt */
+#define SPICC_RH_EN	BIT(4) /* RX FIFO Half-Full Interrupt */
+#define SPICC_RF_EN	BIT(5) /* RX FIFO Full Interrupt */
+#define SPICC_RO_EN	BIT(6) /* RX FIFO Overflow Interrupt */
+#define SPICC_TC_EN	BIT(7) /* Transfert Complete Interrupt */
+
+#define SPICC_DMAREG	0x10
+#define SPICC_DMA_ENABLE		BIT(0)
+#define SPICC_TXFIFO_THRESHOLD_MASK	GENMASK(5, 1)
+#define SPICC_RXFIFO_THRESHOLD_MASK	GENMASK(10, 6)
+#define SPICC_READ_BURST_MASK		GENMASK(14, 11)
+#define SPICC_WRITE_BURST_MASK		GENMASK(18, 15)
+#define SPICC_DMA_URGENT		BIT(19)
+#define SPICC_DMA_THREADID_MASK		GENMASK(25, 20)
+#define SPICC_DMA_BURSTNUM_MASK		GENMASK(31, 26)
+
+#define SPICC_STATREG	0x14
+#define SPICC_TE	BIT(0) /* TX FIFO Empty Interrupt */
+#define SPICC_TH	BIT(1) /* TX FIFO Half-Full Interrupt */
+#define SPICC_TF	BIT(2) /* TX FIFO Full Interrupt */
+#define SPICC_RR	BIT(3) /* RX FIFO Ready Interrupt */
+#define SPICC_RH	BIT(4) /* RX FIFO Half-Full Interrupt */
+#define SPICC_RF	BIT(5) /* RX FIFO Full Interrupt */
+#define SPICC_RO	BIT(6) /* RX FIFO Overflow Interrupt */
+#define SPICC_TC	BIT(7) /* Transfert Complete Interrupt */
+
+#define SPICC_PERIODREG	0x18
+#define SPICC_PERIOD	GENMASK(14, 0)	/* Wait cycles */
+
+#define SPICC_TESTREG	0x1c
+#define SPICC_TXCNT_MASK	GENMASK(4, 0)	/* TX FIFO Counter */
+#define SPICC_RXCNT_MASK	GENMASK(9, 5)	/* RX FIFO Counter */
+#define SPICC_SMSTATUS_MASK	GENMASK(12, 10)	/* State Machine Status */
+#define SPICC_LBC_RO		BIT(13)	/* Loop Back Control Read-Only */
+#define SPICC_LBC_W1		BIT(14) /* Loop Back Control Write-Only */
+#define SPICC_SWAP_RO		BIT(14) /* RX FIFO Data Swap Read-Only */
+#define SPICC_SWAP_W1		BIT(15) /* RX FIFO Data Swap Write-Only */
+#define SPICC_DLYCTL_RO_MASK	GENMASK(20, 15) /* Delay Control Read-Only */
+#define SPICC_DLYCTL_W1_MASK	GENMASK(21, 16) /* Delay Control Write-Only */
+#define SPICC_FIFORST_RO_MASK	GENMASK(22, 21) /* FIFO Softreset Read-Only */
+#define SPICC_FIFORST_W1_MASK	GENMASK(23, 22) /* FIFO Softreset Write-Only */
+
+#define SPICC_DRADDR	0x20	/* Read Address of DMA */
+
+#define SPICC_DWADDR	0x24	/* Write Address of DMA */
+
+#define writel_bits_relaxed(mask, val, addr) \
+	writel_relaxed((readl_relaxed(addr) & ~(mask)) | (val), addr)
+
+#define SPICC_BURST_MAX	16
+#define SPICC_FIFO_HALF 10
+
+struct meson_spicc_device {
+	struct spi_master		*master;
+	struct platform_device		*pdev;
+	void __iomem			*base;
+	struct clk			*core;
+	struct spi_message		*message;
+	struct spi_transfer		*xfer;
+	u8				*tx_buf;
+	u8				*rx_buf;
+	unsigned int			bytes_per_word;
+	unsigned long			tx_remain;
+	unsigned long			txb_remain;
+	unsigned long			rx_remain;
+	unsigned long			rxb_remain;
+	unsigned long			xfer_remain;
+	bool				is_burst_end;
+	bool				is_last_burst;
+};
+
+static inline bool meson_spicc_txfull(struct meson_spicc_device *spicc)
+{
+	return !!FIELD_GET(SPICC_TF,
+			   readl_relaxed(spicc->base + SPICC_STATREG));
+}
+
+static inline bool meson_spicc_rxready(struct meson_spicc_device *spicc)
+{
+	return FIELD_GET(SPICC_RH | SPICC_RR | SPICC_RF_EN,
+			 readl_relaxed(spicc->base + SPICC_STATREG));
+}
+
+static inline u32 meson_spicc_pull_data(struct meson_spicc_device *spicc)
+{
+	unsigned int bytes = spicc->bytes_per_word;
+	unsigned int byte_shift = 0;
+	u32 data = 0;
+	u8 byte;
+
+	while (bytes--) {
+		byte = *spicc->tx_buf++;
+		data |= (byte & 0xff) << byte_shift;
+		byte_shift += 8;
+	}
+
+	spicc->tx_remain--;
+	return data;
+}
+
+static inline void meson_spicc_push_data(struct meson_spicc_device *spicc,
+					 u32 data)
+{
+	unsigned int bytes = spicc->bytes_per_word;
+	unsigned int byte_shift = 0;
+	u8 byte;
+
+	while (bytes--) {
+		byte = (data >> byte_shift) & 0xff;
+		*spicc->rx_buf++ = byte;
+		byte_shift += 8;
+	}
+
+	spicc->rx_remain--;
+}
+
+static inline void meson_spicc_rx(struct meson_spicc_device *spicc)
+{
+	/* Empty RX FIFO */
+	while (spicc->rx_remain &&
+	       meson_spicc_rxready(spicc))
+		meson_spicc_push_data(spicc,
+				readl_relaxed(spicc->base + SPICC_RXDATA));
+}
+
+static inline void meson_spicc_tx(struct meson_spicc_device *spicc)
+{
+	/* Fill Up TX FIFO */
+	while (spicc->tx_remain &&
+	       !meson_spicc_txfull(spicc))
+		writel_relaxed(meson_spicc_pull_data(spicc),
+			       spicc->base + SPICC_TXDATA);
+}
+
+static inline u32 meson_spicc_setup_rx_irq(struct meson_spicc_device *spicc,
+					   u32 irq_ctrl)
+{
+	if (spicc->rx_remain > SPICC_FIFO_HALF)
+		irq_ctrl |= SPICC_RH_EN;
+	else
+		irq_ctrl |= SPICC_RR_EN;
+
+	return irq_ctrl;
+}
+
+static inline void meson_spicc_setup_burst(struct meson_spicc_device *spicc,
+					   unsigned int burst_len)
+{
+	/* Setup Xfer variables */
+	spicc->tx_remain = burst_len;
+	spicc->rx_remain = burst_len;
+	spicc->xfer_remain -= burst_len * spicc->bytes_per_word;
+	spicc->is_burst_end = false;
+	if (burst_len < SPICC_BURST_MAX || !spicc->xfer_remain)
+		spicc->is_last_burst = true;
+	else
+		spicc->is_last_burst = false;
+
+	/* Setup burst length */
+	writel_bits_relaxed(SPICC_BURSTLENGTH_MASK,
+			FIELD_PREP(SPICC_BURSTLENGTH_MASK,
+				burst_len),
+			spicc->base + SPICC_CONREG);
+
+	/* Fill TX FIFO */
+	meson_spicc_tx(spicc);
+}
+
+static irqreturn_t meson_spicc_irq(int irq, void *data)
+{
+	struct meson_spicc_device *spicc = (void *) data;
+	u32 ctrl = readl_relaxed(spicc->base + SPICC_INTREG);
+	u32 stat = readl_relaxed(spicc->base + SPICC_STATREG) & ctrl;
+
+	ctrl &= ~(SPICC_RH_EN | SPICC_RR_EN);
+
+	/* Empty RX FIFO */
+	meson_spicc_rx(spicc);
+
+	/* Enable TC interrupt since we transferred everything */
+	if (!spicc->tx_remain && !spicc->rx_remain) {
+		spicc->is_burst_end = true;
+
+		/* Enable TC interrupt */
+		ctrl |= SPICC_TC_EN;
+
+		/* Reload IRQ status */
+		stat = readl_relaxed(spicc->base + SPICC_STATREG) & ctrl;
+	}
+
+	/* Check transfer complete */
+	if ((stat & SPICC_TC) && spicc->is_burst_end) {
+		unsigned int burst_len;
+
+		/* Clear TC bit */
+		writel_relaxed(SPICC_TC, spicc->base + SPICC_STATREG);
+
+		/* Disable TC interrupt */
+		ctrl &= ~SPICC_TC_EN;
+
+		if (spicc->is_last_burst) {
+			/* Disable all IRQs */
+			writel(0, spicc->base + SPICC_INTREG);
+
+			spi_finalize_current_transfer(spicc->master);
+
+			return IRQ_HANDLED;
+		}
+
+		burst_len = min_t(unsigned int,
+				  spicc->xfer_remain / spicc->bytes_per_word,
+				  SPICC_BURST_MAX);
+
+		/* Setup burst */
+		meson_spicc_setup_burst(spicc, burst_len);
+
+		/* Restart burst */
+		writel_bits_relaxed(SPICC_XCH, SPICC_XCH,
+				    spicc->base + SPICC_CONREG);
+	}
+
+	/* Setup RX interrupt trigger */
+	ctrl = meson_spicc_setup_rx_irq(spicc, ctrl);
+
+	/* Reconfigure interrupts */
+	writel(ctrl, spicc->base + SPICC_INTREG);
+
+	return IRQ_HANDLED;
+}
+
+static u32 meson_spicc_setup_speed(struct meson_spicc_device *spicc, u32 conf,
+				   u32 speed)
+{
+	unsigned long parent, value;
+	unsigned int i, div;
+
+	parent = clk_get_rate(spicc->core);
+
+	/* Find closest inferior/equal possible speed */
+	for (i = 0 ; i < 7 ; ++i) {
+		/* 2^(data_rate+2) */
+		value = parent >> (i + 2);
+
+		if (value <= speed)
+			break;
+	}
+
+	/* If provided speed it lower than max divider, use max divider */
+	if (i > 7) {
+		div = 7;
+		dev_warn_once(&spicc->pdev->dev, "unable to get close to speed %u\n",
+			      speed);
+	} else
+		div = i;
+
+	dev_dbg(&spicc->pdev->dev, "parent %lu, speed %u -> %lu (%u)\n",
+		parent, speed, value, div);
+
+	conf &= ~SPICC_DATARATE_MASK;
+	conf |= FIELD_PREP(SPICC_DATARATE_MASK, div);
+
+	return conf;
+}
+
+static void meson_spicc_setup_xfer(struct meson_spicc_device *spicc,
+				   struct spi_transfer *xfer)
+{
+	u32 conf, conf_orig;
+
+	/* Read original configuration */
+	conf = conf_orig = readl_relaxed(spicc->base + SPICC_CONREG);
+
+	/* Select closest divider */
+	conf = meson_spicc_setup_speed(spicc, conf, xfer->speed_hz);
+
+	/* Setup word width */
+	conf &= ~SPICC_BITLENGTH_MASK;
+	conf |= FIELD_PREP(SPICC_BITLENGTH_MASK,
+			   (spicc->bytes_per_word << 3) - 1);
+
+	/* Ignore if unchanged */
+	if (conf != conf_orig)
+		writel_relaxed(conf, spicc->base + SPICC_CONREG);
+}
+
+static int meson_spicc_transfer_one(struct spi_master *master,
+				    struct spi_device *spi,
+				    struct spi_transfer *xfer)
+{
+	struct meson_spicc_device *spicc = spi_master_get_devdata(master);
+	unsigned int burst_len;
+	u32 irq = 0;
+
+	/* Store current transfer */
+	spicc->xfer = xfer;
+
+	/* Setup transfer parameters */
+	spicc->tx_buf = (u8 *)xfer->tx_buf;
+	spicc->rx_buf = (u8 *)xfer->rx_buf;
+	spicc->xfer_remain = xfer->len;
+
+	/* Pre-calculate word size */
+	spicc->bytes_per_word =
+	   DIV_ROUND_UP(spicc->xfer->bits_per_word, 8);
+
+	/* Setup transfer parameters */
+	meson_spicc_setup_xfer(spicc, xfer);
+
+	burst_len = min_t(unsigned int,
+			  spicc->xfer_remain / spicc->bytes_per_word,
+			  SPICC_BURST_MAX);
+
+	meson_spicc_setup_burst(spicc, burst_len);
+
+	irq = meson_spicc_setup_rx_irq(spicc, irq);
+
+	/* Start burst */
+	writel_bits_relaxed(SPICC_XCH, SPICC_XCH, spicc->base + SPICC_CONREG);
+
+	/* Enable interrupts */
+	writel_relaxed(irq, spicc->base + SPICC_INTREG);
+
+	return 1;
+}
+
+static int meson_spicc_prepare_message(struct spi_master *master,
+				       struct spi_message *message)
+{
+	struct meson_spicc_device *spicc = spi_master_get_devdata(master);
+	struct spi_device *spi = message->spi;
+	u32 conf = 0;
+
+	/* Store current message */
+	spicc->message = message;
+
+	/* Enable Master */
+	conf |= SPICC_ENABLE;
+	conf |= SPICC_MODE_MASTER;
+
+	/* SMC = 0 */
+
+	/* Setup transfer mode */
+	if (spi->mode & SPI_CPOL)
+		conf |= SPICC_POL;
+	else
+		conf &= ~SPICC_POL;
+
+	if (spi->mode & SPI_CPHA)
+		conf |= SPICC_PHA;
+	else
+		conf &= ~SPICC_PHA;
+
+	/* SSCTL = 0 */
+
+	if (spi->mode & SPI_CS_HIGH)
+		conf |= SPICC_SSPOL;
+	else
+		conf &= ~SPICC_SSPOL;
+
+	if (spi->mode & SPI_READY)
+		conf |= FIELD_PREP(SPICC_DRCTL_MASK, SPICC_DRCTL_LOWLEVEL);
+	else
+		conf |= FIELD_PREP(SPICC_DRCTL_MASK, SPICC_DRCTL_IGNORE);
+
+	/* Select CS */
+	conf |= FIELD_PREP(SPICC_CS_MASK, spi->chip_select);
+
+	/* Default Clock rate core/4 */
+
+	/* Default 8bit word */
+	conf |= FIELD_PREP(SPICC_BITLENGTH_MASK, 8 - 1);
+
+	writel_relaxed(conf, spicc->base + SPICC_CONREG);
+
+	/* Setup no wait cycles by default */
+	writel_relaxed(0, spicc->base + SPICC_PERIODREG);
+
+	writel_bits_relaxed(BIT(24), BIT(24), spicc->base + SPICC_TESTREG);
+
+	return 0;
+}
+
+static int meson_spicc_unprepare_transfer(struct spi_master *master)
+{
+	struct meson_spicc_device *spicc = spi_master_get_devdata(master);
+
+	/* Disable all IRQs */
+	writel(0, spicc->base + SPICC_INTREG);
+
+	/* Disable controller */
+	writel_bits_relaxed(SPICC_ENABLE, 0, spicc->base + SPICC_CONREG);
+
+	device_reset_optional(&spicc->pdev->dev);
+
+	return 0;
+}
+
+static int meson_spicc_setup(struct spi_device *spi)
+{
+	int ret = 0;
+
+	if (!spi->controller_state)
+		spi->controller_state = spi_master_get_devdata(spi->master);
+	else if (gpio_is_valid(spi->cs_gpio))
+		goto out_gpio;
+	else if (spi->cs_gpio == -ENOENT)
+		return 0;
+
+	if (gpio_is_valid(spi->cs_gpio)) {
+		ret = gpio_request(spi->cs_gpio, dev_name(&spi->dev));
+		if (ret) {
+			dev_err(&spi->dev, "failed to request cs gpio\n");
+			return ret;
+		}
+	}
+
+out_gpio:
+	ret = gpio_direction_output(spi->cs_gpio,
+			!(spi->mode & SPI_CS_HIGH));
+
+	return ret;
+}
+
+static void meson_spicc_cleanup(struct spi_device *spi)
+{
+	if (gpio_is_valid(spi->cs_gpio))
+		gpio_free(spi->cs_gpio);
+
+	spi->controller_state = NULL;
+}
+
+static int meson_spicc_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct meson_spicc_device *spicc;
+	struct resource *res;
+	int ret, irq, rate;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(*spicc));
+	if (!master) {
+		dev_err(&pdev->dev, "master allocation failed\n");
+		return -ENOMEM;
+	}
+	spicc = spi_master_get_devdata(master);
+	spicc->master = master;
+
+	spicc->pdev = pdev;
+	platform_set_drvdata(pdev, spicc);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	spicc->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(spicc->base)) {
+		dev_err(&pdev->dev, "io resource mapping failed\n");
+		ret = PTR_ERR(spicc->base);
+		goto out_master;
+	}
+
+	/* Disable all IRQs */
+	writel_relaxed(0, spicc->base + SPICC_INTREG);
+
+	irq = platform_get_irq(pdev, 0);
+	ret = devm_request_irq(&pdev->dev, irq, meson_spicc_irq,
+			       0, NULL, spicc);
+	if (ret) {
+		dev_err(&pdev->dev, "irq request failed\n");
+		goto out_master;
+	}
+
+	spicc->core = devm_clk_get(&pdev->dev, "core");
+	if (IS_ERR(spicc->core)) {
+		dev_err(&pdev->dev, "core clock request failed\n");
+		ret = PTR_ERR(spicc->core);
+		goto out_master;
+	}
+
+	ret = clk_prepare_enable(spicc->core);
+	if (ret) {
+		dev_err(&pdev->dev, "core clock enable failed\n");
+		goto out_master;
+	}
+	rate = clk_get_rate(spicc->core);
+
+	device_reset_optional(&pdev->dev);
+
+	master->num_chipselect = 4;
+	master->dev.of_node = pdev->dev.of_node;
+	master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_CS_HIGH;
+	master->bits_per_word_mask = SPI_BPW_MASK(32) |
+				     SPI_BPW_MASK(24) |
+				     SPI_BPW_MASK(16) |
+				     SPI_BPW_MASK(8);
+	master->flags = (SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX);
+	master->min_speed_hz = rate >> 9;
+	master->setup = meson_spicc_setup;
+	master->cleanup = meson_spicc_cleanup;
+	master->prepare_message = meson_spicc_prepare_message;
+	master->unprepare_transfer_hardware = meson_spicc_unprepare_transfer;
+	master->transfer_one = meson_spicc_transfer_one;
+
+	/* Setup max rate according to the Meson GX datasheet */
+	if ((rate >> 2) > SPICC_MAX_FREQ)
+		master->max_speed_hz = SPICC_MAX_FREQ;
+	else
+		master->max_speed_hz = rate >> 2;
+
+	ret = devm_spi_register_master(&pdev->dev, master);
+	if (!ret)
+		return 0;
+
+	dev_err(&pdev->dev, "spi master registration failed\n");
+
+out_master:
+	spi_master_put(master);
+
+	return ret;
+}
+
+static int meson_spicc_remove(struct platform_device *pdev)
+{
+	struct meson_spicc_device *spicc = platform_get_drvdata(pdev);
+
+	/* Disable SPI */
+	writel(0, spicc->base + SPICC_CONREG);
+
+	clk_disable_unprepare(spicc->core);
+
+	return 0;
+}
+
+static const struct of_device_id meson_spicc_of_match[] = {
+	{ .compatible = "amlogic,meson-gx-spicc", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, meson_spicc_of_match);
+
+static struct platform_driver meson_spicc_driver = {
+	.probe   = meson_spicc_probe,
+	.remove  = meson_spicc_remove,
+	.driver  = {
+		.name = "meson-spicc",
+		.of_match_table = of_match_ptr(meson_spicc_of_match),
+	},
+};
+
+module_platform_driver(meson_spicc_driver);
+
+MODULE_DESCRIPTION("Meson SPI Communication Controller driver");
+MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
+MODULE_LICENSE("GPL");
-- 
2.11.0