spi: new controller driver for efm32 SoCs

Signed-off-by: Uwe Kleine-König <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/spi/efm32-spi.txt

···
+* Energy Micro EFM32 SPI
+
+Required properties:
+- #address-cells: see spi-bus.txt
+- #size-cells: see spi-bus.txt
+- compatible: should be "efm32,spi"
+- reg: Offset and length of the register set for the controller
+- interrupts: pair specifying rx and tx irq
+- clocks: phandle to the spi clock
+- cs-gpios: see spi-bus.txt
+- location: Value to write to the ROUTE register's LOCATION bitfield to configure the pinmux for the device, see datasheet for values.
+
+Example:
+
+spi1: spi@0x4000c400 { /* USART1 */
+	#address-cells = <1>;
+	#size-cells = <0>;
+	compatible = "efm32,spi";
+	reg = <0x4000c400 0x400>;
+	interrupts = <15 16>;
+	clocks = <&cmu 20>;
+	cs-gpios = <&gpio 51 1>; // D3
+	location = <1>;
+	status = "ok";
+
+	ks8851@0 {
+		compatible = "ks8851";
+		spi-max-frequency = <6000000>;
+		reg = <0>;
+		interrupt-parent = <&boardfpga>;
+		interrupts = <4>;
+		status = "ok";
+	};
+};

drivers/spi/Kconfig

···
 	help
 	  SPI master controller for DaVinci/DA8x/OMAP-L/AM1x SPI modules.
 
+config SPI_EFM32
+	tristate "EFM32 SPI controller"
+	depends on OF && ARM && (ARCH_EFM32 || COMPILE_TEST)
+	select SPI_BITBANG
+	help
+	  Driver for the spi controller found on Energy Micro's EFM32 SoCs.
+
 config SPI_EP93XX
 	tristate "Cirrus Logic EP93xx SPI controller"
 	depends on ARCH_EP93XX

drivers/spi/Makefile

···
 obj-$(CONFIG_SPI_DW_MMIO)		+= spi-dw-mmio.o
 obj-$(CONFIG_SPI_DW_PCI)		+= spi-dw-midpci.o
 spi-dw-midpci-objs			:= spi-dw-pci.o spi-dw-mid.o
+obj-$(CONFIG_SPI_EFM32)			+= spi-efm32.o
 obj-$(CONFIG_SPI_EP93XX)		+= spi-ep93xx.o
 obj-$(CONFIG_SPI_FALCON)		+= spi-falcon.o
 obj-$(CONFIG_SPI_FSL_CPM)		+= spi-fsl-cpm.o

drivers/spi/spi-efm32.c

···
+/*
+ * Copyright (C) 2012-2013 Uwe Kleine-Koenig for Pengutronix
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation.
+ */
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+#include <linux/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_data/efm32-spi.h>
+
+#define DRIVER_NAME "efm32-spi"
+
+#define MASK_VAL(mask, val)		((val << __ffs(mask)) & mask)
+
+#define REG_CTRL		0x00
+#define REG_CTRL_SYNC			0x0001
+#define REG_CTRL_CLKPOL			0x0100
+#define REG_CTRL_CLKPHA			0x0200
+#define REG_CTRL_MSBF			0x0400
+#define REG_CTRL_TXBIL			0x1000
+
+#define REG_FRAME		0x04
+#define REG_FRAME_DATABITS__MASK	0x000f
+#define REG_FRAME_DATABITS(n)		((n) - 3)
+
+#define REG_CMD			0x0c
+#define REG_CMD_RXEN			0x0001
+#define REG_CMD_RXDIS			0x0002
+#define REG_CMD_TXEN			0x0004
+#define REG_CMD_TXDIS			0x0008
+#define REG_CMD_MASTEREN		0x0010
+
+#define REG_STATUS		0x10
+#define REG_STATUS_TXENS		0x0002
+#define REG_STATUS_TXC			0x0020
+#define REG_STATUS_TXBL			0x0040
+#define REG_STATUS_RXDATAV		0x0080
+
+#define REG_CLKDIV		0x14
+
+#define REG_RXDATAX		0x18
+#define REG_RXDATAX_RXDATA__MASK	0x01ff
+#define REG_RXDATAX_PERR		0x4000
+#define REG_RXDATAX_FERR		0x8000
+
+#define REG_TXDATA		0x34
+
+#define REG_IF		0x40
+#define REG_IF_TXBL			0x0002
+#define REG_IF_RXDATAV			0x0004
+
+#define REG_IFS		0x44
+#define REG_IFC		0x48
+#define REG_IEN		0x4c
+
+#define REG_ROUTE		0x54
+#define REG_ROUTE_RXPEN			0x0001
+#define REG_ROUTE_TXPEN			0x0002
+#define REG_ROUTE_CLKPEN		0x0008
+#define REG_ROUTE_LOCATION__MASK	0x0700
+#define REG_ROUTE_LOCATION(n)		MASK_VAL(REG_ROUTE_LOCATION__MASK, (n))
+
+struct efm32_spi_ddata {
+	struct spi_bitbang bitbang;
+
+	spinlock_t lock;
+
+	struct clk *clk;
+	void __iomem *base;
+	unsigned int rxirq, txirq;
+	struct efm32_spi_pdata pdata;
+
+	/* irq data */
+	struct completion done;
+	const u8 *tx_buf;
+	u8 *rx_buf;
+	unsigned tx_len, rx_len;
+
+	/* chip selects */
+	unsigned csgpio[];
+};
+
+#define ddata_to_dev(ddata)	(&(ddata->bitbang.master->dev))
+#define efm32_spi_vdbg(ddata, format, arg...)	\
+	dev_vdbg(ddata_to_dev(ddata), format, ##arg)
+
+static void efm32_spi_write32(struct efm32_spi_ddata *ddata,
+		u32 value, unsigned offset)
+{
+	writel_relaxed(value, ddata->base + offset);
+}
+
+static u32 efm32_spi_read32(struct efm32_spi_ddata *ddata, unsigned offset)
+{
+	return readl_relaxed(ddata->base + offset);
+}
+
+static void efm32_spi_chipselect(struct spi_device *spi, int is_on)
+{
+	struct efm32_spi_ddata *ddata = spi_master_get_devdata(spi->master);
+	int value = !(spi->mode & SPI_CS_HIGH) == !(is_on == BITBANG_CS_ACTIVE);
+
+	gpio_set_value(ddata->csgpio[spi->chip_select], value);
+}
+
+static int efm32_spi_setup_transfer(struct spi_device *spi,
+		struct spi_transfer *t)
+{
+	struct efm32_spi_ddata *ddata = spi_master_get_devdata(spi->master);
+
+	unsigned bpw = t->bits_per_word ?: spi->bits_per_word;
+	unsigned speed = t->speed_hz ?: spi->max_speed_hz;
+	unsigned long clkfreq = clk_get_rate(ddata->clk);
+	u32 clkdiv;
+
+	efm32_spi_write32(ddata, REG_CTRL_SYNC | REG_CTRL_MSBF |
+			(spi->mode & SPI_CPHA ? REG_CTRL_CLKPHA : 0) |
+			(spi->mode & SPI_CPOL ? REG_CTRL_CLKPOL : 0), REG_CTRL);
+
+	efm32_spi_write32(ddata,
+			REG_FRAME_DATABITS(bpw), REG_FRAME);
+
+	if (2 * speed >= clkfreq)
+		clkdiv = 0;
+	else
+		clkdiv = 64 * (DIV_ROUND_UP(2 * clkfreq, speed) - 4);
+
+	if (clkdiv > (1U << 21))
+		return -EINVAL;
+
+	efm32_spi_write32(ddata, clkdiv, REG_CLKDIV);
+	efm32_spi_write32(ddata, REG_CMD_MASTEREN, REG_CMD);
+	efm32_spi_write32(ddata, REG_CMD_RXEN | REG_CMD_TXEN, REG_CMD);
+
+	return 0;
+}
+
+static void efm32_spi_tx_u8(struct efm32_spi_ddata *ddata)
+{
+	u8 val = 0;
+
+	if (ddata->tx_buf) {
+		val = *ddata->tx_buf;
+		ddata->tx_buf++;
+	}
+
+	ddata->tx_len--;
+	efm32_spi_write32(ddata, val, REG_TXDATA);
+	efm32_spi_vdbg(ddata, "%s: tx 0x%x\n", __func__, val);
+}
+
+static void efm32_spi_rx_u8(struct efm32_spi_ddata *ddata)
+{
+	u32 rxdata = efm32_spi_read32(ddata, REG_RXDATAX);
+	efm32_spi_vdbg(ddata, "%s: rx 0x%x\n", __func__, rxdata);
+
+	if (ddata->rx_buf) {
+		*ddata->rx_buf = rxdata;
+		ddata->rx_buf++;
+	}
+
+	ddata->rx_len--;
+}
+
+static void efm32_spi_filltx(struct efm32_spi_ddata *ddata)
+{
+	while (ddata->tx_len &&
+			ddata->tx_len + 2 > ddata->rx_len &&
+			efm32_spi_read32(ddata, REG_STATUS) & REG_STATUS_TXBL) {
+		efm32_spi_tx_u8(ddata);
+	}
+}
+
+static int efm32_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct efm32_spi_ddata *ddata = spi_master_get_devdata(spi->master);
+	int ret = -EBUSY;
+
+	spin_lock_irq(&ddata->lock);
+
+	if (ddata->tx_buf || ddata->rx_buf)
+		goto out_unlock;
+
+	ddata->tx_buf = t->tx_buf;
+	ddata->rx_buf = t->rx_buf;
+	ddata->tx_len = ddata->rx_len =
+		t->len * DIV_ROUND_UP(t->bits_per_word, 8);
+
+	efm32_spi_filltx(ddata);
+
+	init_completion(&ddata->done);
+
+	efm32_spi_write32(ddata, REG_IF_TXBL | REG_IF_RXDATAV, REG_IEN);
+
+	spin_unlock_irq(&ddata->lock);
+
+	wait_for_completion(&ddata->done);
+
+	spin_lock_irq(&ddata->lock);
+
+	ret = t->len - max(ddata->tx_len, ddata->rx_len);
+
+	efm32_spi_write32(ddata, 0, REG_IEN);
+	ddata->tx_buf = ddata->rx_buf = NULL;
+
+out_unlock:
+	spin_unlock_irq(&ddata->lock);
+
+	return ret;
+}
+
+static irqreturn_t efm32_spi_rxirq(int irq, void *data)
+{
+	struct efm32_spi_ddata *ddata = data;
+	irqreturn_t ret = IRQ_NONE;
+
+	spin_lock(&ddata->lock);
+
+	while (ddata->rx_len > 0 &&
+			efm32_spi_read32(ddata, REG_STATUS) &
+			REG_STATUS_RXDATAV) {
+		efm32_spi_rx_u8(ddata);
+
+		ret = IRQ_HANDLED;
+	}
+
+	if (!ddata->rx_len) {
+		u32 ien = efm32_spi_read32(ddata, REG_IEN);
+
+		ien &= ~REG_IF_RXDATAV;
+
+		efm32_spi_write32(ddata, ien, REG_IEN);
+
+		complete(&ddata->done);
+	}
+
+	spin_unlock(&ddata->lock);
+
+	return ret;
+}
+
+static irqreturn_t efm32_spi_txirq(int irq, void *data)
+{
+	struct efm32_spi_ddata *ddata = data;
+
+	efm32_spi_vdbg(ddata,
+			"%s: txlen = %u, rxlen = %u, if=0x%08x, stat=0x%08x\n",
+			__func__, ddata->tx_len, ddata->rx_len,
+			efm32_spi_read32(ddata, REG_IF),
+			efm32_spi_read32(ddata, REG_STATUS));
+
+	spin_lock(&ddata->lock);
+
+	efm32_spi_filltx(ddata);
+
+	efm32_spi_vdbg(ddata, "%s: txlen = %u, rxlen = %u\n",
+			__func__, ddata->tx_len, ddata->rx_len);
+
+	if (!ddata->tx_len) {
+		u32 ien = efm32_spi_read32(ddata, REG_IEN);
+
+		ien &= ~REG_IF_TXBL;
+
+		efm32_spi_write32(ddata, ien, REG_IEN);
+		efm32_spi_vdbg(ddata, "disable TXBL\n");
+	}
+
+	spin_unlock(&ddata->lock);
+
+	return IRQ_HANDLED;
+}
+
+static const struct efm32_spi_pdata efm32_spi_pdata_default = {
+	.location = 1,
+};
+
+static u32 efm32_spi_get_configured_location(struct efm32_spi_ddata *ddata)
+{
+	u32 reg = efm32_spi_read32(ddata, REG_ROUTE);
+
+	return (reg & REG_ROUTE_LOCATION__MASK) >> __ffs(REG_ROUTE_LOCATION__MASK);
+}
+
+static int efm32_spi_probe_dt(struct platform_device *pdev,
+		struct spi_master *master, struct efm32_spi_ddata *ddata)
+{
+	struct device_node *np = pdev->dev.of_node;
+	u32 location;
+	int ret;
+
+	if (!np)
+		return 1;
+
+	ret = of_property_read_u32(np, "location", &location);
+	if (!ret) {
+		dev_dbg(&pdev->dev, "using location %u\n", location);
+	} else {
+		/* default to location configured in hardware */
+		location = efm32_spi_get_configured_location(ddata);
+
+		dev_info(&pdev->dev, "fall back to location %u\n", location);
+	}
+
+	ddata->pdata.location = location;
+
+	/* spi core takes care about the bus number using an alias */
+	master->bus_num = -1;
+
+	return 0;
+}
+
+static int efm32_spi_probe(struct platform_device *pdev)
+{
+	struct efm32_spi_ddata *ddata;
+	struct resource *res;
+	int ret;
+	struct spi_master *master;
+	struct device_node *np = pdev->dev.of_node;
+	unsigned int num_cs, i;
+
+	num_cs = of_gpio_named_count(np, "cs-gpios");
+
+	master = spi_alloc_master(&pdev->dev,
+			sizeof(*ddata) + num_cs * sizeof(unsigned));
+	if (!master) {
+		dev_dbg(&pdev->dev,
+				"failed to allocate spi master controller\n");
+		return -ENOMEM;
+	}
+	platform_set_drvdata(pdev, master);
+
+	master->dev.of_node = pdev->dev.of_node;
+
+	master->num_chipselect = num_cs;
+	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 16);
+
+	ddata = spi_master_get_devdata(master);
+
+	ddata->bitbang.master = spi_master_get(master);
+	ddata->bitbang.chipselect = efm32_spi_chipselect;
+	ddata->bitbang.setup_transfer = efm32_spi_setup_transfer;
+	ddata->bitbang.txrx_bufs = efm32_spi_txrx_bufs;
+
+	spin_lock_init(&ddata->lock);
+
+	ddata->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(ddata->clk)) {
+		ret = PTR_ERR(ddata->clk);
+		dev_err(&pdev->dev, "failed to get clock: %d\n", ret);
+		goto err;
+	}
+
+	for (i = 0; i < num_cs; ++i) {
+		ret = of_get_named_gpio(np, "cs-gpios", i);
+		if (ret < 0) {
+			dev_err(&pdev->dev, "failed to get csgpio#%u (%d)\n",
+					i, ret);
+			goto err;
+		}
+		ddata->csgpio[i] = ret;
+		dev_dbg(&pdev->dev, "csgpio#%u = %u\n", i, ddata->csgpio[i]);
+		ret = devm_gpio_request_one(&pdev->dev, ddata->csgpio[i],
+				GPIOF_OUT_INIT_LOW, DRIVER_NAME);
+		if (ret < 0) {
+			dev_err(&pdev->dev,
+					"failed to configure csgpio#%u (%d)\n",
+					i, ret);
+			goto err;
+		}
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		ret = -ENODEV;
+		dev_err(&pdev->dev, "failed to determine base address\n");
+		goto err;
+	}
+
+	if (resource_size(res) < 60) {
+		ret = -EINVAL;
+		dev_err(&pdev->dev, "memory resource too small\n");
+		goto err;
+	}
+
+	ddata->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(ddata->base)) {
+		ret = PTR_ERR(ddata->base);
+		dev_err(&pdev->dev, "failed to remap memory\n");
+		goto err;
+	}
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret <= 0) {
+		dev_err(&pdev->dev, "failed to get rx irq (%d)\n", ret);
+		goto err;
+	}
+
+	ddata->rxirq = ret;
+
+	ret = platform_get_irq(pdev, 1);
+	if (ret <= 0)
+		ret = ddata->rxirq + 1;
+
+	ddata->txirq = ret;
+
+	ret = clk_prepare_enable(ddata->clk);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to enable clock (%d)\n", ret);
+		goto err;
+	}
+
+	ret = efm32_spi_probe_dt(pdev, master, ddata);
+	if (ret > 0) {
+		/* not created by device tree */
+		const struct efm32_spi_pdata *pdata =
+			dev_get_platdata(&pdev->dev);
+
+		if (pdata)
+			ddata->pdata = *pdata;
+		else
+			ddata->pdata.location =
+				efm32_spi_get_configured_location(ddata);
+
+		master->bus_num = pdev->id;
+
+	} else if (ret < 0) {
+		goto err_disable_clk;
+	}
+
+	efm32_spi_write32(ddata, 0, REG_IEN);
+	efm32_spi_write32(ddata, REG_ROUTE_TXPEN | REG_ROUTE_RXPEN |
+			REG_ROUTE_CLKPEN |
+			REG_ROUTE_LOCATION(ddata->pdata.location), REG_ROUTE);
+
+	ret = request_irq(ddata->rxirq, efm32_spi_rxirq,
+			0, DRIVER_NAME " rx", ddata);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register rxirq (%d)\n", ret);
+		goto err_disable_clk;
+	}
+
+	ret = request_irq(ddata->txirq, efm32_spi_txirq,
+			0, DRIVER_NAME " tx", ddata);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register txirq (%d)\n", ret);
+		goto err_free_rx_irq;
+	}
+
+	ret = spi_bitbang_start(&ddata->bitbang);
+	if (ret) {
+		dev_err(&pdev->dev, "spi_bitbang_start failed (%d)\n", ret);
+
+		free_irq(ddata->txirq, ddata);
+err_free_rx_irq:
+		free_irq(ddata->rxirq, ddata);
+err_disable_clk:
+		clk_disable_unprepare(ddata->clk);
+err:
+		spi_master_put(master);
+		kfree(master);
+	}
+
+	return ret;
+}
+
+static int efm32_spi_remove(struct platform_device *pdev)
+{
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct efm32_spi_ddata *ddata = spi_master_get_devdata(master);
+
+	efm32_spi_write32(ddata, 0, REG_IEN);
+
+	free_irq(ddata->txirq, ddata);
+	free_irq(ddata->rxirq, ddata);
+	clk_disable_unprepare(ddata->clk);
+	spi_master_put(master);
+	kfree(master);
+
+	return 0;
+}
+
+static const struct of_device_id efm32_spi_dt_ids[] = {
+	{
+		.compatible = "efm32,spi",
+	}, {
+		/* sentinel */
+	}
+};
+MODULE_DEVICE_TABLE(of, efm32_uart_dt_ids);
+
+static struct platform_driver efm32_spi_driver = {
+	.probe = efm32_spi_probe,
+	.remove = efm32_spi_remove,
+
+	.driver = {
+		.name = DRIVER_NAME,
+		.owner = THIS_MODULE,
+		.of_match_table = efm32_spi_dt_ids,
+	},
+};
+module_platform_driver(efm32_spi_driver);
+
+MODULE_AUTHOR("Uwe Kleine-Koenig <[e-mail]>");
+MODULE_DESCRIPTION("EFM32 SPI driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" DRIVER_NAME);

include/linux/platform_data/efm32-spi.h

···
+#ifndef __LINUX_PLATFORM_DATA_EFM32_SPI_H__
+#define __LINUX_PLATFORM_DATA_EFM32_SPI_H__
+
+#include <linux/types.h>
+
+/**
+ * struct efm32_spi_pdata
+ * @location: pinmux location for the I/O pins (to be written to the ROUTE
+ * 	register)
+ */
+struct efm32_spi_pdata {
+	u8 location;
+};
+#endif /* ifndef __LINUX_PLATFORM_DATA_EFM32_SPI_H__ */