spi: sunxi: Add Allwinner A31 SPI controller driver

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>;

};

	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

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

/*

 * 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");