spi: sunxi: Add Allwinner A31 SPI controller driver

The Allwinner A31 has a new SPI controller IP compared to the older Allwinner
SoCs.

It supports DMA, but the driver only does PIO for now, and DMA will be
supported eventually.
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

Documentation/devicetree/bindings/spi/spi-sun6i.txt

+Allwinner A31 SPI controller
+
+Required properties:
+- compatible: Should be "allwinner,sun6i-a31-spi".
+- reg: Should contain register location and length.
+- interrupts: Should contain interrupt.
+- clocks: phandle to the clocks feeding the SPI controller. Two are
+          needed:
+  - "ahb": the gated AHB parent clock
+  - "mod": the parent module clock
+- clock-names: Must contain the clock names described just above
+- resets: phandle to the reset controller asserting this device in
+          reset
+
+Example:
+
+spi1: spi@01c69000 {
+	compatible = "allwinner,sun6i-a31-spi";
+	reg = <0x01c69000 0x1000>;
+	interrupts = <0 66 4>;
+	clocks = <&ahb1_gates 21>, <&spi1_clk>;
+	clock-names = "ahb", "mod";
+	resets = <&ahb1_rst 21>;
+};

drivers/spi/Kconfig

@@ -446,6 +446,12 @@ config SPI_SIRF
 	help
 	  SPI driver for CSR SiRFprimaII SoCs
 
+config SPI_SUN6I
+	tristate "Allwinner A31 SPI controller"
+	depends on ARCH_SUNXI || COMPILE_TEST
+	help
+	  This enables using the SPI controller on the Allwinner A31 SoCs.
+
 config SPI_MXS
 	tristate "Freescale MXS SPI controller"
 	depends on ARCH_MXS

drivers/spi/Makefile

@@ -70,6 +70,7 @@ obj-$(CONFIG_SPI_SH_HSPI)		+= spi-sh-hspi.o
 obj-$(CONFIG_SPI_SH_MSIOF)		+= spi-sh-msiof.o
 obj-$(CONFIG_SPI_SH_SCI)		+= spi-sh-sci.o
 obj-$(CONFIG_SPI_SIRF)		+= spi-sirf.o
+obj-$(CONFIG_SPI_SUN6I)			+= spi-sun6i.o
 obj-$(CONFIG_SPI_TEGRA114)		+= spi-tegra114.o
 obj-$(CONFIG_SPI_TEGRA20_SFLASH)	+= spi-tegra20-sflash.o
 obj-$(CONFIG_SPI_TEGRA20_SLINK)		+= spi-tegra20-slink.o

drivers/spi/spi-sun6i.c

+/*
+ * Copyright (C) 2012 - 2014 Allwinner Tech
+ * Pan Nan <pannan@allwinnertech.com>
+ *
+ * Copyright (C) 2014 Maxime Ripard
+ * Maxime Ripard <maxime.ripard@free-electrons.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/reset.h>
+#include <linux/workqueue.h>
+
+#include <linux/spi/spi.h>
+
+#define SUN6I_FIFO_DEPTH		128
+
+#define SUN6I_GBL_CTL_REG		0x04
+#define SUN6I_GBL_CTL_BUS_ENABLE		BIT(0)
+#define SUN6I_GBL_CTL_MASTER			BIT(1)
+#define SUN6I_GBL_CTL_TP			BIT(7)
+#define SUN6I_GBL_CTL_RST			BIT(31)
+
+#define SUN6I_TFR_CTL_REG		0x08
+#define SUN6I_TFR_CTL_CPHA			BIT(0)
+#define SUN6I_TFR_CTL_CPOL			BIT(1)
+#define SUN6I_TFR_CTL_SPOL			BIT(2)
+#define SUN6I_TFR_CTL_CS_MASK			0x3
+#define SUN6I_TFR_CTL_CS(cs)			(((cs) & SUN6I_TFR_CTL_CS_MASK) << 4)
+#define SUN6I_TFR_CTL_CS_MANUAL			BIT(6)
+#define SUN6I_TFR_CTL_CS_LEVEL			BIT(7)
+#define SUN6I_TFR_CTL_DHB			BIT(8)
+#define SUN6I_TFR_CTL_FBS			BIT(12)
+#define SUN6I_TFR_CTL_XCH			BIT(31)
+
+#define SUN6I_INT_CTL_REG		0x10
+#define SUN6I_INT_CTL_RF_OVF			BIT(8)
+#define SUN6I_INT_CTL_TC			BIT(12)
+
+#define SUN6I_INT_STA_REG		0x14
+
+#define SUN6I_FIFO_CTL_REG		0x18
+#define SUN6I_FIFO_CTL_RF_RST			BIT(15)
+#define SUN6I_FIFO_CTL_TF_RST			BIT(31)
+
+#define SUN6I_FIFO_STA_REG		0x1c
+#define SUN6I_FIFO_STA_RF_CNT_MASK		0x7f
+#define SUN6I_FIFO_STA_RF_CNT_BITS		0
+#define SUN6I_FIFO_STA_TF_CNT_MASK		0x7f
+#define SUN6I_FIFO_STA_TF_CNT_BITS		16
+
+#define SUN6I_CLK_CTL_REG		0x24
+#define SUN6I_CLK_CTL_CDR2_MASK			0xff
+#define SUN6I_CLK_CTL_CDR2(div)			(((div) & SUN6I_CLK_CTL_CDR2_MASK) << 0)
+#define SUN6I_CLK_CTL_CDR1_MASK			0xf
+#define SUN6I_CLK_CTL_CDR1(div)			(((div) & SUN6I_CLK_CTL_CDR1_MASK) << 8)
+#define SUN6I_CLK_CTL_DRS			BIT(12)
+
+#define SUN6I_BURST_CNT_REG		0x30
+#define SUN6I_BURST_CNT(cnt)			((cnt) & 0xffffff)
+
+#define SUN6I_XMIT_CNT_REG		0x34
+#define SUN6I_XMIT_CNT(cnt)			((cnt) & 0xffffff)
+
+#define SUN6I_BURST_CTL_CNT_REG		0x38
+#define SUN6I_BURST_CTL_CNT_STC(cnt)		((cnt) & 0xffffff)
+
+#define SUN6I_TXDATA_REG		0x200
+#define SUN6I_RXDATA_REG		0x300
+
+struct sun6i_spi {
+	struct spi_master	*master;
+	void __iomem		*base_addr;
+	struct clk		*hclk;
+	struct clk		*mclk;
+	struct reset_control	*rstc;
+
+	struct completion	done;
+
+	const u8		*tx_buf;
+	u8			*rx_buf;
+	int			len;
+};
+
+static inline u32 sun6i_spi_read(struct sun6i_spi *sspi, u32 reg)
+{
+	return readl(sspi->base_addr + reg);
+}
+
+static inline void sun6i_spi_write(struct sun6i_spi *sspi, u32 reg, u32 value)
+{
+	writel(value, sspi->base_addr + reg);
+}
+
+static inline void sun6i_spi_drain_fifo(struct sun6i_spi *sspi, int len)
+{
+	u32 reg, cnt;
+	u8 byte;
+
+	/* See how much data is available */
+	reg = sun6i_spi_read(sspi, SUN6I_FIFO_STA_REG);
+	reg &= SUN6I_FIFO_STA_RF_CNT_MASK;
+	cnt = reg >> SUN6I_FIFO_STA_RF_CNT_BITS;
+
+	if (len > cnt)
+		len = cnt;
+
+	while (len--) {
+		byte = readb(sspi->base_addr + SUN6I_RXDATA_REG);
+		if (sspi->rx_buf)
+			*sspi->rx_buf++ = byte;
+	}
+}
+
+static inline void sun6i_spi_fill_fifo(struct sun6i_spi *sspi, int len)
+{
+	u8 byte;
+
+	if (len > sspi->len)
+		len = sspi->len;
+
+	while (len--) {
+		byte = sspi->tx_buf ? *sspi->tx_buf++ : 0;
+		writeb(byte, sspi->base_addr + SUN6I_TXDATA_REG);
+		sspi->len--;
+	}
+}
+
+static void sun6i_spi_set_cs(struct spi_device *spi, bool enable)
+{
+	struct sun6i_spi *sspi = spi_master_get_devdata(spi->master);
+	u32 reg;
+
+	reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
+	reg &= ~SUN6I_TFR_CTL_CS_MASK;
+	reg |= SUN6I_TFR_CTL_CS(spi->chip_select);
+
+	if (enable)
+		reg |= SUN6I_TFR_CTL_CS_LEVEL;
+	else
+		reg &= ~SUN6I_TFR_CTL_CS_LEVEL;
+
+	sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg);
+}
+
+
+static int sun6i_spi_transfer_one(struct spi_master *master,
+				  struct spi_device *spi,
+				  struct spi_transfer *tfr)
+{
+	struct sun6i_spi *sspi = spi_master_get_devdata(master);
+	unsigned int mclk_rate, div, timeout;
+	unsigned int tx_len = 0;
+	int ret = 0;
+	u32 reg;
+
+	/* We don't support transfer larger than the FIFO */
+	if (tfr->len > SUN6I_FIFO_DEPTH)
+		return -EINVAL;
+
+	reinit_completion(&sspi->done);
+	sspi->tx_buf = tfr->tx_buf;
+	sspi->rx_buf = tfr->rx_buf;
+	sspi->len = tfr->len;
+
+	/* Clear pending interrupts */
+	sun6i_spi_write(sspi, SUN6I_INT_STA_REG, ~0);
+
+	/* Reset FIFO */
+	sun6i_spi_write(sspi, SUN6I_FIFO_CTL_REG,
+			SUN6I_FIFO_CTL_RF_RST | SUN6I_FIFO_CTL_TF_RST);
+
+	/*
+	 * Setup the transfer control register: Chip Select,
+	 * polarities, etc.
+	 */
+	reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
+
+	if (spi->mode & SPI_CPOL)
+		reg |= SUN6I_TFR_CTL_CPOL;
+	else
+		reg &= ~SUN6I_TFR_CTL_CPOL;
+
+	if (spi->mode & SPI_CPHA)
+		reg |= SUN6I_TFR_CTL_CPHA;
+	else
+		reg &= ~SUN6I_TFR_CTL_CPHA;
+
+	if (spi->mode & SPI_LSB_FIRST)
+		reg |= SUN6I_TFR_CTL_FBS;
+	else
+		reg &= ~SUN6I_TFR_CTL_FBS;
+
+	/*
+	 * If it's a TX only transfer, we don't want to fill the RX
+	 * FIFO with bogus data
+	 */
+	if (sspi->rx_buf)
+		reg &= ~SUN6I_TFR_CTL_DHB;
+	else
+		reg |= SUN6I_TFR_CTL_DHB;
+
+	/* We want to control the chip select manually */
+	reg |= SUN6I_TFR_CTL_CS_MANUAL;
+
+	sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg);
+
+	/* Ensure that we have a parent clock fast enough */
+	mclk_rate = clk_get_rate(sspi->mclk);
+	if (mclk_rate < (2 * spi->max_speed_hz)) {
+		clk_set_rate(sspi->mclk, 2 * spi->max_speed_hz);
+		mclk_rate = clk_get_rate(sspi->mclk);
+	}
+
+	/*
+	 * Setup clock divider.
+	 *
+	 * We have two choices there. Either we can use the clock
+	 * divide rate 1, which is calculated thanks to this formula:
+	 * SPI_CLK = MOD_CLK / (2 ^ cdr)
+	 * Or we can use CDR2, which is calculated with the formula:
+	 * SPI_CLK = MOD_CLK / (2 * (cdr + 1))
+	 * Wether we use the former or the latter is set through the
+	 * DRS bit.
+	 *
+	 * First try CDR2, and if we can't reach the expected
+	 * frequency, fall back to CDR1.
+	 */
+	div = mclk_rate / (2 * spi->max_speed_hz);
+	if (div <= (SUN6I_CLK_CTL_CDR2_MASK + 1)) {
+		if (div > 0)
+			div--;
+
+		reg = SUN6I_CLK_CTL_CDR2(div) | SUN6I_CLK_CTL_DRS;
+	} else {
+		div = ilog2(mclk_rate) - ilog2(spi->max_speed_hz);
+		reg = SUN6I_CLK_CTL_CDR1(div);
+	}
+
+	sun6i_spi_write(sspi, SUN6I_CLK_CTL_REG, reg);
+
+	/* Setup the transfer now... */
+	if (sspi->tx_buf)
+		tx_len = tfr->len;
+
+	/* Setup the counters */
+	sun6i_spi_write(sspi, SUN6I_BURST_CNT_REG, SUN6I_BURST_CNT(tfr->len));
+	sun6i_spi_write(sspi, SUN6I_XMIT_CNT_REG, SUN6I_XMIT_CNT(tx_len));
+	sun6i_spi_write(sspi, SUN6I_BURST_CTL_CNT_REG,
+			SUN6I_BURST_CTL_CNT_STC(tx_len));
+
+	/* Fill the TX FIFO */
+	sun6i_spi_fill_fifo(sspi, SUN6I_FIFO_DEPTH);
+
+	/* Enable the interrupts */
+	sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, SUN6I_INT_CTL_TC);
+
+	/* Start the transfer */
+	reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
+	sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg | SUN6I_TFR_CTL_XCH);
+
+	timeout = wait_for_completion_timeout(&sspi->done,
+					      msecs_to_jiffies(1000));
+	if (!timeout) {
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+
+	sun6i_spi_drain_fifo(sspi, SUN6I_FIFO_DEPTH);
+
+out:
+	sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, 0);
+
+	return ret;
+}
+
+static irqreturn_t sun6i_spi_handler(int irq, void *dev_id)
+{
+	struct sun6i_spi *sspi = dev_id;
+	u32 status = sun6i_spi_read(sspi, SUN6I_INT_STA_REG);
+
+	/* Transfer complete */
+	if (status & SUN6I_INT_CTL_TC) {
+		sun6i_spi_write(sspi, SUN6I_INT_STA_REG, SUN6I_INT_CTL_TC);
+		complete(&sspi->done);
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
+static int sun6i_spi_runtime_resume(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct sun6i_spi *sspi = spi_master_get_devdata(master);
+	int ret;
+
+	ret = clk_prepare_enable(sspi->hclk);
+	if (ret) {
+		dev_err(dev, "Couldn't enable AHB clock\n");
+		goto out;
+	}
+
+	ret = clk_prepare_enable(sspi->mclk);
+	if (ret) {
+		dev_err(dev, "Couldn't enable module clock\n");
+		goto err;
+	}
+
+	ret = reset_control_deassert(sspi->rstc);
+	if (ret) {
+		dev_err(dev, "Couldn't deassert the device from reset\n");
+		goto err2;
+	}
+
+	sun6i_spi_write(sspi, SUN6I_GBL_CTL_REG,
+			SUN6I_GBL_CTL_BUS_ENABLE | SUN6I_GBL_CTL_MASTER | SUN6I_GBL_CTL_TP);
+
+	return 0;
+
+err2:
+	clk_disable_unprepare(sspi->mclk);
+err:
+	clk_disable_unprepare(sspi->hclk);
+out:
+	return ret;
+}
+
+static int sun6i_spi_runtime_suspend(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct sun6i_spi *sspi = spi_master_get_devdata(master);
+
+	reset_control_assert(sspi->rstc);
+	clk_disable_unprepare(sspi->mclk);
+	clk_disable_unprepare(sspi->hclk);
+
+	return 0;
+}
+
+static int sun6i_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct sun6i_spi *sspi;
+	struct resource	*res;
+	int ret = 0, irq;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct sun6i_spi));
+	if (!master) {
+		dev_err(&pdev->dev, "Unable to allocate SPI Master\n");
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, master);
+	sspi = spi_master_get_devdata(master);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	sspi->base_addr = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(sspi->base_addr)) {
+		ret = PTR_ERR(sspi->base_addr);
+		goto err_free_master;
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "No spi IRQ specified\n");
+		ret = -ENXIO;
+		goto err_free_master;
+	}
+
+	ret = devm_request_irq(&pdev->dev, irq, sun6i_spi_handler,
+			       0, "sun6i-spi", sspi);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot request IRQ\n");
+		goto err_free_master;
+	}
+
+	sspi->master = master;
+	master->set_cs = sun6i_spi_set_cs;
+	master->transfer_one = sun6i_spi_transfer_one;
+	master->num_chipselect = 4;
+	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST;
+	master->dev.of_node = pdev->dev.of_node;
+	master->auto_runtime_pm = true;
+
+	sspi->hclk = devm_clk_get(&pdev->dev, "ahb");
+	if (IS_ERR(sspi->hclk)) {
+		dev_err(&pdev->dev, "Unable to acquire AHB clock\n");
+		ret = PTR_ERR(sspi->hclk);
+		goto err_free_master;
+	}
+
+	sspi->mclk = devm_clk_get(&pdev->dev, "mod");
+	if (IS_ERR(sspi->mclk)) {
+		dev_err(&pdev->dev, "Unable to acquire module clock\n");
+		ret = PTR_ERR(sspi->mclk);
+		goto err_free_master;
+	}
+
+	init_completion(&sspi->done);
+
+	sspi->rstc = devm_reset_control_get(&pdev->dev, NULL);
+	if (IS_ERR(sspi->rstc)) {
+		dev_err(&pdev->dev, "Couldn't get reset controller\n");
+		ret = PTR_ERR(sspi->rstc);
+		goto err_free_master;
+	}
+
+	/*
+	 * This wake-up/shutdown pattern is to be able to have the
+	 * device woken up, even if runtime_pm is disabled
+	 */
+	ret = sun6i_spi_runtime_resume(&pdev->dev);
+	if (ret) {
+		dev_err(&pdev->dev, "Couldn't resume the device\n");
+		goto err_free_master;
+	}
+
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+	pm_runtime_idle(&pdev->dev);
+
+	ret = devm_spi_register_master(&pdev->dev, master);
+	if (ret) {
+		dev_err(&pdev->dev, "cannot register SPI master\n");
+		goto err_pm_disable;
+	}
+
+	return 0;
+
+err_pm_disable:
+	pm_runtime_disable(&pdev->dev);
+	sun6i_spi_runtime_suspend(&pdev->dev);
+err_free_master:
+	spi_master_put(master);
+	return ret;
+}
+
+static int sun6i_spi_remove(struct platform_device *pdev)
+{
+	pm_runtime_disable(&pdev->dev);
+
+	return 0;
+}
+
+static const struct of_device_id sun6i_spi_match[] = {
+	{ .compatible = "allwinner,sun6i-a31-spi", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, sun6i_spi_match);
+
+static const struct dev_pm_ops sun6i_spi_pm_ops = {
+	.runtime_resume		= sun6i_spi_runtime_resume,
+	.runtime_suspend	= sun6i_spi_runtime_suspend,
+};
+
+static struct platform_driver sun6i_spi_driver = {
+	.probe	= sun6i_spi_probe,
+	.remove	= sun6i_spi_remove,
+	.driver	= {
+		.name		= "sun6i-spi",
+		.owner		= THIS_MODULE,
+		.of_match_table	= sun6i_spi_match,
+		.pm		= &sun6i_spi_pm_ops,
+	},
+};
+module_platform_driver(sun6i_spi_driver);
+
+MODULE_AUTHOR("Pan Nan <pannan@allwinnertech.com>");
+MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
+MODULE_DESCRIPTION("Allwinner A31 SPI controller driver");
+MODULE_LICENSE("GPL");