[PATCH v7 1/2] spi: implemented driver for Cirrus EP93xx SPI controller
Mika Westerberg
mika.westerberg at iki.fi
Thu May 6 00:47:04 EDT 2010
This patch adds an SPI master driver for the Cirrus EP93xx SPI controller found
in EP93xx chips.
Signed-off-by: Mika Westerberg <mika.westerberg at iki.fi>
Signed-off-by: H Hartley Sweeten <hsweeten at visionengravers.com>
Acked-by: H Hartley Sweeten <hsweeten at visionengravers.com>
Cc: Ryan Mallon <ryan at bluewatersys.com>
Cc: David Brownell <dbrownell at users.sourceforge.net>
Cc: Grant Likely <grant.likely at secretlab.ca>
Cc: Martin Guy <martinwguy at gmail.com>
---
Documentation/spi/ep93xx_spi | 95 +++
arch/arm/mach-ep93xx/include/mach/ep93xx_spi.h | 27 +
drivers/spi/Kconfig | 10 +
drivers/spi/Makefile | 1 +
drivers/spi/ep93xx_spi.c | 938 ++++++++++++++++++++++++
5 files changed, 1071 insertions(+), 0 deletions(-)
create mode 100644 Documentation/spi/ep93xx_spi
create mode 100644 arch/arm/mach-ep93xx/include/mach/ep93xx_spi.h
create mode 100644 drivers/spi/ep93xx_spi.c
diff --git a/Documentation/spi/ep93xx_spi b/Documentation/spi/ep93xx_spi
new file mode 100644
index 0000000..6325f5b
--- /dev/null
+++ b/Documentation/spi/ep93xx_spi
@@ -0,0 +1,95 @@
+Cirrus EP93xx SPI controller driver HOWTO
+=========================================
+
+ep93xx_spi driver brings SPI master support for EP93xx SPI controller. Chip
+selects are implemented with GPIO lines.
+
+NOTE: If possible, don't use SFRMOUT (SFRM1) signal as a chip select. It will
+not work correctly (it cannot be controlled by software). Use GPIO lines
+instead.
+
+Sample configuration
+====================
+
+Typically driver configuration is done in platform board files (the files under
+arch/arm/mach-ep93xx/*.c). In this example we configure MMC over SPI through
+this driver on TS-7260 board. You can adapt the code to suit your needs.
+
+This example uses EGPIO9 as SD/MMC card chip select (this is wired in DIO1
+header on the board).
+
+You need to select CONFIG_MMC_SPI to use mmc_spi driver.
+
+arch/arm/mach-ep93xx/ts72xx.c:
+
+...
+#include <linux/gpio.h>
+#include <linux/spi/spi.h>
+
+#include <mach/ep93xx_spi.h>
+
+/* this is our GPIO line used for chip select */
+#define MMC_CHIP_SELECT_GPIO EP93XX_GPIO_LINE_EGPIO9
+
+static int ts72xx_mmc_spi_setup(struct spi_device *spi)
+{
+ int err;
+
+ err = gpio_request(MMC_CHIP_SELECT_GPIO, spi->modalias);
+ if (err)
+ return err;
+
+ gpio_direction_output(MMC_CHIP_SELECT_GPIO, 1);
+
+ return 0;
+}
+
+static void ts72xx_mmc_spi_cleanup(struct spi_device *spi)
+{
+ gpio_set_value(MMC_CHIP_SELECT_GPIO, 1);
+ gpio_direction_input(MMC_CHIP_SELECT_GPIO);
+ gpio_free(MMC_CHIP_SELECT_GPIO);
+}
+
+static void ts72xx_mmc_spi_cs_control(struct spi_device *spi, int value)
+{
+ gpio_set_value(MMC_CHIP_SELECT_GPIO, value);
+}
+
+static struct ep93xx_spi_chip_ops ts72xx_mmc_spi_ops = {
+ .setup = ts72xx_mmc_spi_setup,
+ .cleanup = ts72xx_mmc_spi_cleanup,
+ .cs_control = ts72xx_mmc_spi_cs_control,
+};
+
+static struct spi_board_info ts72xx_spi_devices[] __initdata = {
+ {
+ .modalias = "mmc_spi",
+ .controller_data = &ts72xx_mmc_spi_ops,
+ /*
+ * We use 10 MHz even though the maximum is 7.4 MHz. The driver
+ * will limit it automatically to max. frequency.
+ */
+ .max_speed_hz = 10 * 1000 * 1000,
+ .bus_num = 0,
+ .chip_select = 0,
+ .mode = SPI_MODE_0,
+ },
+};
+
+static struct ep93xx_spi_info ts72xx_spi_info = {
+ .num_chipselect = ARRAY_SIZE(ts72xx_spi_devices),
+};
+
+static void __init ts72xx_init_machine(void)
+{
+ ...
+ ep93xx_register_spi(&ts72xx_spi_info, ts72xx_spi_devices,
+ ARRAY_SIZE(ts72xx_spi_devices));
+}
+
+Thanks to
+=========
+Martin Guy, H. Hartley Sweeten and others who helped me during development of
+the driver. Simplemachines.it donated me a Sim.One board which I used testing
+the driver on EP9307.
diff --git a/arch/arm/mach-ep93xx/include/mach/ep93xx_spi.h b/arch/arm/mach-ep93xx/include/mach/ep93xx_spi.h
new file mode 100644
index 0000000..0a37961
--- /dev/null
+++ b/arch/arm/mach-ep93xx/include/mach/ep93xx_spi.h
@@ -0,0 +1,27 @@
+#ifndef __ASM_MACH_EP93XX_SPI_H
+#define __ASM_MACH_EP93XX_SPI_H
+
+struct spi_device;
+
+/**
+ * struct ep93xx_spi_info - EP93xx specific SPI descriptor
+ * @num_chipselect: number of chip selects on this board, must be
+ * at least one
+ */
+struct ep93xx_spi_info {
+ int num_chipselect;
+};
+
+/**
+ * struct ep93xx_spi_chip_ops - operation callbacks for SPI slave device
+ * @setup: setup the chip select mechanism
+ * @cleanup: cleanup the chip select mechanism
+ * @cs_control: control the device chip select
+ */
+struct ep93xx_spi_chip_ops {
+ int (*setup)(struct spi_device *spi);
+ void (*cleanup)(struct spi_device *spi);
+ void (*cs_control)(struct spi_device *spi, int value);
+};
+
+#endif /* __ASM_MACH_EP93XX_SPI_H */
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index a191fa2..2b2f4c3 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -117,6 +117,16 @@ config SPI_DAVINCI
help
SPI master controller for DaVinci and DA8xx SPI modules.
+config SPI_EP93XX
+ tristate "Cirrus Logic EP93xx SPI controller"
+ depends on ARCH_EP93XX
+ help
+ This enables using the Cirrus EP93xx SPI controller in master
+ mode.
+
+ To compile this driver as a module, choose M here. The module will be
+ called ep93xx_spi.
+
config SPI_GPIO
tristate "GPIO-based bitbanging SPI Master"
depends on GENERIC_GPIO
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index d7d0f89..377f845 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_SPI_DAVINCI) += davinci_spi.o
obj-$(CONFIG_SPI_DESIGNWARE) += dw_spi.o
obj-$(CONFIG_SPI_DW_PCI) += dw_spi_pci.o
obj-$(CONFIG_SPI_DW_MMIO) += dw_spi_mmio.o
+obj-$(CONFIG_SPI_EP93XX) += ep93xx_spi.o
obj-$(CONFIG_SPI_GPIO) += spi_gpio.o
obj-$(CONFIG_SPI_IMX) += spi_imx.o
obj-$(CONFIG_SPI_LM70_LLP) += spi_lm70llp.o
diff --git a/drivers/spi/ep93xx_spi.c b/drivers/spi/ep93xx_spi.c
new file mode 100644
index 0000000..0ba35df
--- /dev/null
+++ b/drivers/spi/ep93xx_spi.c
@@ -0,0 +1,938 @@
+/*
+ * Driver for Cirrus Logic EP93xx SPI controller.
+ *
+ * Copyright (c) 2010 Mika Westerberg
+ *
+ * Explicit FIFO handling code was inspired by amba-pl022 driver.
+ *
+ * Chip select support using other than built-in GPIOs by H. Hartley Sweeten.
+ *
+ * For more information about the SPI controller see documentation on Cirrus
+ * Logic web site:
+ * http://www.cirrus.com/en/pubs/manual/EP93xx_Users_Guide_UM1.pdf
+ *
+ * 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/io.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/bitops.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/workqueue.h>
+#include <linux/sched.h>
+#include <linux/spi/spi.h>
+
+#include <mach/ep93xx_spi.h>
+
+#define SSPCR0 0x0000
+#define SSPCR0_MODE_SHIFT 6
+#define SSPCR0_SCR_SHIFT 8
+
+#define SSPCR1 0x0004
+#define SSPCR1_RIE BIT(0)
+#define SSPCR1_TIE BIT(1)
+#define SSPCR1_RORIE BIT(2)
+#define SSPCR1_LBM BIT(3)
+#define SSPCR1_SSE BIT(4)
+#define SSPCR1_MS BIT(5)
+#define SSPCR1_SOD BIT(6)
+
+#define SSPDR 0x0008
+
+#define SSPSR 0x000c
+#define SSPSR_TFE BIT(0)
+#define SSPSR_TNF BIT(1)
+#define SSPSR_RNE BIT(2)
+#define SSPSR_RFF BIT(3)
+#define SSPSR_BSY BIT(4)
+#define SSPCPSR 0x0010
+
+#define SSPIIR 0x0014
+#define SSPIIR_RIS BIT(0)
+#define SSPIIR_TIS BIT(1)
+#define SSPIIR_RORIS BIT(2)
+#define SSPICR SSPIIR
+
+/* timeout in milliseconds */
+#define SPI_TIMEOUT 5
+/* maximum depth of RX/TX FIFO */
+#define SPI_FIFO_SIZE 8
+
+/**
+ * struct ep93xx_spi - EP93xx SPI controller structure
+ * @lock: spinlock that protects concurrent accesses to fields @running,
+ * @current_msg and @msg_queue
+ * @pdev: pointer to platform device
+ * @clk: clock for the controller
+ * @regs_base: pointer to ioremap()'d registers
+ * @irq: IRQ number used by the driver
+ * @min_rate: minimum clock rate (in Hz) supported by the controller
+ * @max_rate: maximum clock rate (in Hz) supported by the controller
+ * @running: is the queue running
+ * @wq: workqueue used by the driver
+ * @msg_work: work that is queued for the driver
+ * @wait: wait here until given transfer is completed
+ * @msg_queue: queue for the messages
+ * @current_msg: message that is currently processed (or %NULL if none)
+ * @tx: current byte in transfer to transmit
+ * @rx: current byte in transfer to receive
+ * @fifo_level: how full is FIFO (%0..%SPI_FIFO_SIZE - %1). Receiving one
+ * frame decreases this level and sending one frame increases it.
+ *
+ * This structure holds EP93xx SPI controller specific information. When
+ * @running is %true, driver accepts transfer requests from protocol drivers.
+ * @current_msg is used to hold pointer to the message that is currently
+ * processed. If @current_msg is %NULL, it means that no processing is going
+ * on.
+ *
+ * Most of the fields are only written once and they can be accessed without
+ * taking the @lock. Fields that are accessed concurrently are: @current_msg,
+ * @running, and @msg_queue.
+ */
+struct ep93xx_spi {
+ spinlock_t lock;
+ const struct platform_device *pdev;
+ struct clk *clk;
+ void __iomem *regs_base;
+ int irq;
+ unsigned long min_rate;
+ unsigned long max_rate;
+ bool running;
+ struct workqueue_struct *wq;
+ struct work_struct msg_work;
+ struct completion wait;
+ struct list_head msg_queue;
+ struct spi_message *current_msg;
+ size_t tx;
+ size_t rx;
+ size_t fifo_level;
+};
+
+/**
+ * struct ep93xx_spi_chip - SPI device hardware settings
+ * @spi: back pointer to the SPI device
+ * @rate: max rate in hz this chip supports
+ * @div_cpsr: cpsr (pre-scaler) divider
+ * @div_scr: scr divider
+ * @dss: bits per word (4 - 16 bits)
+ * @ops: private chip operations
+ *
+ * This structure is used to store hardware register specific settings for each
+ * SPI device. Settings are written to hardware by function
+ * ep93xx_spi_chip_setup().
+ */
+struct ep93xx_spi_chip {
+ const struct spi_device *spi;
+ unsigned long rate;
+ u8 div_cpsr;
+ u8 div_scr;
+ u8 dss;
+ struct ep93xx_spi_chip_ops *ops;
+};
+
+/* converts bits per word to CR0.DSS value */
+#define bits_per_word_to_dss(bpw) ((bpw) - 1)
+
+static inline void
+ep93xx_spi_write_u8(const struct ep93xx_spi *espi, u16 reg, u8 value)
+{
+ __raw_writeb(value, espi->regs_base + reg);
+}
+
+static inline u8
+ep93xx_spi_read_u8(const struct ep93xx_spi *spi, u16 reg)
+{
+ return __raw_readb(spi->regs_base + reg);
+}
+
+static inline void
+ep93xx_spi_write_u16(const struct ep93xx_spi *espi, u16 reg, u16 value)
+{
+ __raw_writew(value, espi->regs_base + reg);
+}
+
+static inline u16
+ep93xx_spi_read_u16(const struct ep93xx_spi *spi, u16 reg)
+{
+ return __raw_readw(spi->regs_base + reg);
+}
+
+static int ep93xx_spi_enable(const struct ep93xx_spi *espi)
+{
+ u8 regval;
+ int err;
+
+ err = clk_enable(espi->clk);
+ if (err)
+ return err;
+
+ regval = ep93xx_spi_read_u8(espi, SSPCR1);
+ regval |= SSPCR1_SSE;
+ ep93xx_spi_write_u8(espi, SSPCR1, regval);
+
+ return 0;
+}
+
+static void ep93xx_spi_disable(const struct ep93xx_spi *espi)
+{
+ u8 regval;
+
+ regval = ep93xx_spi_read_u8(espi, SSPCR1);
+ regval &= ~SSPCR1_SSE;
+ ep93xx_spi_write_u8(espi, SSPCR1, regval);
+
+ clk_disable(espi->clk);
+}
+
+static void ep93xx_spi_enable_interrupts(const struct ep93xx_spi *espi)
+{
+ u8 regval;
+
+ regval = ep93xx_spi_read_u8(espi, SSPCR1);
+ regval |= (SSPCR1_RORIE | SSPCR1_TIE | SSPCR1_RIE);
+ ep93xx_spi_write_u8(espi, SSPCR1, regval);
+}
+
+static void ep93xx_spi_disable_interrupts(const struct ep93xx_spi *espi)
+{
+ u8 regval;
+
+ regval = ep93xx_spi_read_u8(espi, SSPCR1);
+ regval &= ~(SSPCR1_RORIE | SSPCR1_TIE | SSPCR1_RIE);
+ ep93xx_spi_write_u8(espi, SSPCR1, regval);
+}
+
+/**
+ * ep93xx_spi_calc_divisors() - calculates SPI clock divisors
+ * @espi: ep93xx SPI controller struct
+ * @chip: divisors are calculated for this chip
+ * @rate: desired SPI output clock rate
+ *
+ * Function calculates cpsr (clock pre-scaler) and scr divisors based on
+ * given @rate and places them to @chip->div_cpsr and @chip->div_scr. If,
+ * for some reason, divisors cannot be calculated nothing is stored and
+ * %-EINVAL is returned.
+ */
+static int ep93xx_spi_calc_divisors(const struct ep93xx_spi *espi,
+ struct ep93xx_spi_chip *chip,
+ unsigned long rate)
+{
+ unsigned long spi_clk_rate = clk_get_rate(espi->clk);
+ int cpsr, scr;
+
+ /*
+ * Make sure that max value is between values supported by the
+ * controller. Note that minimum value is already checked in
+ * ep93xx_spi_transfer().
+ */
+ rate = clamp(rate, espi->min_rate, espi->max_rate);
+
+ /*
+ * Calculate divisors so that we can get speed according the
+ * following formula:
+ * rate = spi_clock_rate / (cpsr * (1 + scr))
+ *
+ * cpsr must be even number and starts from 2, scr can be any number
+ * between 0 and 255.
+ */
+ for (cpsr = 2; cpsr <= 254; cpsr += 2) {
+ for (scr = 0; scr <= 255; scr++) {
+ if ((spi_clk_rate / (cpsr * (scr + 1))) <= rate) {
+ chip->div_scr = (u8)scr;
+ chip->div_cpsr = (u8)cpsr;
+ return 0;
+ }
+ }
+ }
+
+ return -EINVAL;
+}
+
+static void ep93xx_spi_cs_control(struct spi_device *spi, bool control)
+{
+ struct ep93xx_spi_chip *chip = spi_get_ctldata(spi);
+ int value = (spi->mode & SPI_CS_HIGH) ? control : !control;
+
+ if (chip->ops && chip->ops->cs_control)
+ chip->ops->cs_control(spi, value);
+}
+
+/**
+ * ep93xx_spi_setup() - setup an SPI device
+ * @spi: SPI device to setup
+ *
+ * This function sets up SPI device mode, speed etc. Can be called multiple
+ * times for a single device. Returns %0 in case of success, negative error in
+ * case of failure. When this function returns success, the device is
+ * deselected.
+ */
+static int ep93xx_spi_setup(struct spi_device *spi)
+{
+ struct ep93xx_spi *espi = spi_master_get_devdata(spi->master);
+ struct ep93xx_spi_chip *chip;
+
+ if (spi->bits_per_word < 4 || spi->bits_per_word > 16) {
+ dev_err(&espi->pdev->dev, "invalid bits per word %d\n",
+ spi->bits_per_word);
+ return -EINVAL;
+ }
+
+ chip = spi_get_ctldata(spi);
+ if (!chip) {
+ dev_dbg(&espi->pdev->dev, "initial setup for %s\n",
+ spi->modalias);
+
+ chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+ if (!chip)
+ return -ENOMEM;
+
+ chip->spi = spi;
+ chip->ops = spi->controller_data;
+
+ if (chip->ops && chip->ops->setup) {
+ int ret = chip->ops->setup(spi);
+ if (ret) {
+ kfree(chip);
+ return ret;
+ }
+ }
+
+ spi_set_ctldata(spi, chip);
+ }
+
+ if (spi->max_speed_hz != chip->rate) {
+ int err;
+
+ err = ep93xx_spi_calc_divisors(espi, chip, spi->max_speed_hz);
+ if (err != 0) {
+ spi_set_ctldata(spi, NULL);
+ kfree(chip);
+ return err;
+ }
+ chip->rate = spi->max_speed_hz;
+ }
+
+ chip->dss = bits_per_word_to_dss(spi->bits_per_word);
+
+ ep93xx_spi_cs_control(spi, false);
+ return 0;
+}
+
+/**
+ * ep93xx_spi_transfer() - queue message to be transferred
+ * @spi: target SPI device
+ * @msg: message to be transferred
+ *
+ * This function is called by SPI device drivers when they are going to transfer
+ * a new message. It simply puts the message in the queue and schedules
+ * workqueue to perform the actual transfer later on.
+ *
+ * Returns %0 on success and negative error in case of failure.
+ */
+static int ep93xx_spi_transfer(struct spi_device *spi, struct spi_message *msg)
+{
+ struct ep93xx_spi *espi = spi_master_get_devdata(spi->master);
+ struct spi_transfer *t;
+ unsigned long flags;
+
+ if (!msg || !msg->complete)
+ return -EINVAL;
+
+ /* first validate each transfer */
+ list_for_each_entry(t, &msg->transfers, transfer_list) {
+ if (t->bits_per_word) {
+ if (t->bits_per_word < 4 || t->bits_per_word > 16)
+ return -EINVAL;
+ }
+ if (t->speed_hz && t->speed_hz < espi->min_rate)
+ return -EINVAL;
+ }
+
+ /*
+ * Now that we own the message, let's initialize it so that it is
+ * suitable for us. We use @msg->status to signal whether there was
+ * error in transfer and @msg->state is used to hold pointer to the
+ * current transfer (or %NULL if no active current transfer).
+ */
+ msg->state = NULL;
+ msg->status = 0;
+ msg->actual_length = 0;
+
+ spin_lock_irqsave(&espi->lock, flags);
+ if (!espi->running) {
+ spin_unlock_irqrestore(&espi->lock, flags);
+ return -ESHUTDOWN;
+ }
+ list_add_tail(&msg->queue, &espi->msg_queue);
+ queue_work(espi->wq, &espi->msg_work);
+ spin_unlock_irqrestore(&espi->lock, flags);
+
+ return 0;
+}
+
+/**
+ * ep93xx_spi_cleanup() - cleans up master controller specific state
+ * @spi: SPI device to cleanup
+ *
+ * This function releases master controller specific state for given @spi
+ * device.
+ */
+static void ep93xx_spi_cleanup(struct spi_device *spi)
+{
+ struct ep93xx_spi_chip *chip;
+
+ chip = spi_get_ctldata(spi);
+ if (chip) {
+ if (chip->ops && chip->ops->cleanup)
+ chip->ops->cleanup(spi);
+ spi_set_ctldata(spi, NULL);
+ kfree(chip);
+ }
+}
+
+/**
+ * ep93xx_spi_chip_setup() - configures hardware according to given @chip
+ * @espi: ep93xx SPI controller struct
+ * @chip: chip specific settings
+ *
+ * This function sets up the actual hardware registers with settings given in
+ * @chip. Note that no validation is done so make sure that callers validate
+ * settings before calling this.
+ */
+static void ep93xx_spi_chip_setup(const struct ep93xx_spi *espi,
+ const struct ep93xx_spi_chip *chip)
+{
+ u16 cr0;
+
+ cr0 = chip->div_scr << SSPCR0_SCR_SHIFT;
+ cr0 |= (chip->spi->mode & (SPI_CPHA|SPI_CPOL)) << SSPCR0_MODE_SHIFT;
+ cr0 |= chip->dss;
+
+ dev_dbg(&espi->pdev->dev, "setup: mode %d, cpsr %d, scr %d, dss %d\n",
+ chip->spi->mode, chip->div_cpsr, chip->div_scr, chip->dss);
+ dev_dbg(&espi->pdev->dev, "setup: cr0 %#x", cr0);
+
+ ep93xx_spi_write_u8(espi, SSPCPSR, chip->div_cpsr);
+ ep93xx_spi_write_u16(espi, SSPCR0, cr0);
+}
+
+static inline int bits_per_word(const struct ep93xx_spi *espi)
+{
+ struct spi_message *msg = espi->current_msg;
+ struct spi_transfer *t = msg->state;
+
+ return t->bits_per_word ? t->bits_per_word : msg->spi->bits_per_word;
+}
+
+static void ep93xx_do_write(struct ep93xx_spi *espi, struct spi_transfer *t)
+{
+ if (bits_per_word(espi) > 8) {
+ u16 tx_val = 0;
+
+ if (t->tx_buf)
+ tx_val = ((u16 *)t->tx_buf)[espi->tx];
+ ep93xx_spi_write_u16(espi, SSPDR, tx_val);
+ espi->tx += sizeof(tx_val);
+ } else {
+ u8 tx_val = 0;
+
+ if (t->tx_buf)
+ tx_val = ((u8 *)t->tx_buf)[espi->tx];
+ ep93xx_spi_write_u8(espi, SSPDR, tx_val);
+ espi->tx += sizeof(tx_val);
+ }
+}
+
+static void ep93xx_do_read(struct ep93xx_spi *espi, struct spi_transfer *t)
+{
+ if (bits_per_word(espi) > 8) {
+ u16 rx_val;
+
+ rx_val = ep93xx_spi_read_u16(espi, SSPDR);
+ if (t->rx_buf)
+ ((u16 *)t->rx_buf)[espi->rx] = rx_val;
+ espi->rx += sizeof(rx_val);
+ } else {
+ u8 rx_val;
+
+ rx_val = ep93xx_spi_read_u8(espi, SSPDR);
+ if (t->rx_buf)
+ ((u8 *)t->rx_buf)[espi->rx] = rx_val;
+ espi->rx += sizeof(rx_val);
+ }
+}
+
+/**
+ * ep93xx_spi_read_write() - perform next RX/TX transfer
+ * @espi: ep93xx SPI controller struct
+ *
+ * This function transfers next bytes (or half-words) to/from RX/TX FIFOs. If
+ * called several times, the whole transfer will be completed. Returns
+ * %-EINPROGRESS when current transfer was not yet completed otherwise %0.
+ *
+ * When this function is finished, RX FIFO should be empty and TX FIFO should be
+ * full.
+ */
+static int ep93xx_spi_read_write(struct ep93xx_spi *espi)
+{
+ struct spi_message *msg = espi->current_msg;
+ struct spi_transfer *t = msg->state;
+
+ /* read as long as RX FIFO has frames in it */
+ while ((ep93xx_spi_read_u8(espi, SSPSR) & SSPSR_RNE)) {
+ ep93xx_do_read(espi, t);
+ espi->fifo_level--;
+ }
+
+ /* write as long as TX FIFO has room */
+ while (espi->fifo_level < SPI_FIFO_SIZE && espi->tx < t->len) {
+ ep93xx_do_write(espi, t);
+ espi->fifo_level++;
+ }
+
+ if (espi->rx == t->len) {
+ msg->actual_length += t->len;
+ return 0;
+ }
+
+ return -EINPROGRESS;
+}
+
+/**
+ * ep93xx_spi_process_transfer() - processes one SPI transfer
+ * @espi: ep93xx SPI controller struct
+ * @msg: current message
+ * @t: transfer to process
+ *
+ * This function processes one SPI transfer given in @t. Function waits until
+ * transfer is complete (may sleep) and updates @msg->status based on whether
+ * transfer was succesfully processed or not.
+ */
+static void ep93xx_spi_process_transfer(struct ep93xx_spi *espi,
+ struct spi_message *msg,
+ struct spi_transfer *t)
+{
+ struct ep93xx_spi_chip *chip = spi_get_ctldata(msg->spi);
+
+ msg->state = t;
+
+ /*
+ * Handle any transfer specific settings if needed. We use
+ * temporary chip settings here and restore original later when
+ * the transfer is finished.
+ */
+ if (t->speed_hz || t->bits_per_word) {
+ struct ep93xx_spi_chip tmp_chip = *chip;
+
+ if (t->speed_hz) {
+ int err;
+
+ err = ep93xx_spi_calc_divisors(espi, &tmp_chip,
+ t->speed_hz);
+ if (err) {
+ dev_err(&espi->pdev->dev,
+ "failed to adjust speed\n");
+ msg->status = err;
+ return;
+ }
+ }
+
+ if (t->bits_per_word)
+ tmp_chip.dss = bits_per_word_to_dss(t->bits_per_word);
+
+ /*
+ * Set up temporary new hw settings for this transfer.
+ */
+ ep93xx_spi_chip_setup(espi, &tmp_chip);
+ }
+
+ espi->rx = 0;
+ espi->tx = 0;
+
+ /*
+ * Now everything is set up for the current transfer. We prime the TX
+ * FIFO, enable interrupts, and wait for the transfer to complete.
+ */
+ if (ep93xx_spi_read_write(espi)) {
+ ep93xx_spi_enable_interrupts(espi);
+ wait_for_completion(&espi->wait);
+ }
+
+ /*
+ * In case of error during transmit, we bail out from processing
+ * the message.
+ */
+ if (msg->status)
+ return;
+
+ /*
+ * After this transfer is finished, perform any possible
+ * post-transfer actions requested by the protocol driver.
+ */
+ if (t->delay_usecs) {
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ schedule_timeout(usecs_to_jiffies(t->delay_usecs));
+ }
+ if (t->cs_change) {
+ if (!list_is_last(&t->transfer_list, &msg->transfers)) {
+ /*
+ * In case protocol driver is asking us to drop the
+ * chipselect briefly, we let the scheduler to handle
+ * any "delay" here.
+ */
+ ep93xx_spi_cs_control(msg->spi, false);
+ cond_resched();
+ ep93xx_spi_cs_control(msg->spi, true);
+ }
+ }
+
+ if (t->speed_hz || t->bits_per_word)
+ ep93xx_spi_chip_setup(espi, chip);
+}
+
+/*
+ * ep93xx_spi_process_message() - process one SPI message
+ * @espi: ep93xx SPI controller struct
+ * @msg: message to process
+ *
+ * This function processes a single SPI message. We go through all transfers in
+ * the message and pass them to ep93xx_spi_process_transfer(). Chipselect is
+ * asserted during the whole message (unless per transfer cs_change is set).
+ *
+ * @msg->status contains %0 in case of success or negative error code in case of
+ * failure.
+ */
+static void ep93xx_spi_process_message(struct ep93xx_spi *espi,
+ struct spi_message *msg)
+{
+ unsigned long timeout;
+ struct spi_transfer *t;
+ int err;
+
+ /*
+ * Enable the SPI controller and its clock.
+ */
+ err = ep93xx_spi_enable(espi);
+ if (err) {
+ dev_err(&espi->pdev->dev, "failed to enable SPI controller\n");
+ msg->status = err;
+ return;
+ }
+
+ /*
+ * Just to be sure: flush any data from RX FIFO.
+ */
+ timeout = jiffies + msecs_to_jiffies(SPI_TIMEOUT);
+ while (ep93xx_spi_read_u16(espi, SSPSR) & SSPSR_RNE) {
+ if (time_after(jiffies, timeout)) {
+ dev_warn(&espi->pdev->dev,
+ "timeout while flushing RX FIFO\n");
+ msg->status = -ETIMEDOUT;
+ return;
+ }
+ ep93xx_spi_read_u16(espi, SSPDR);
+ }
+
+ /*
+ * We explicitly handle FIFO level. This way we don't have to check TX
+ * FIFO status using %SSPSR_TNF bit which may cause RX FIFO overruns.
+ */
+ espi->fifo_level = 0;
+
+ /*
+ * Update SPI controller registers according to spi device and assert
+ * the chipselect.
+ */
+ ep93xx_spi_chip_setup(espi, spi_get_ctldata(msg->spi));
+ ep93xx_spi_cs_control(msg->spi, true);
+
+ list_for_each_entry(t, &msg->transfers, transfer_list) {
+ ep93xx_spi_process_transfer(espi, msg, t);
+ if (msg->status)
+ break;
+ }
+
+ /*
+ * Now the whole message is transferred (or failed for some reason). We
+ * deselect the device and disable the SPI controller.
+ */
+ ep93xx_spi_cs_control(msg->spi, false);
+ ep93xx_spi_disable(espi);
+}
+
+#define work_to_espi(work) (container_of((work), struct ep93xx_spi, msg_work))
+
+/**
+ * ep93xx_spi_work() - EP93xx SPI workqueue worker function
+ * @work: work struct
+ *
+ * Workqueue worker function. This function is called when there are new
+ * SPI messages to be processed. Message is taken out from the queue and then
+ * passed to ep93xx_spi_process_message().
+ *
+ * After message is transferred, protocol driver is notified by calling
+ * @msg->complete(). In case of error, @msg->status is set to negative error
+ * number, otherwise it contains zero (and @msg->actual_length is updated).
+ */
+static void ep93xx_spi_work(struct work_struct *work)
+{
+ struct ep93xx_spi *espi = work_to_espi(work);
+ struct spi_message *msg;
+
+ spin_lock_irq(&espi->lock);
+ if (!espi->running || espi->current_msg ||
+ list_empty(&espi->msg_queue)) {
+ spin_unlock_irq(&espi->lock);
+ return;
+ }
+ msg = list_first_entry(&espi->msg_queue, struct spi_message, queue);
+ list_del_init(&msg->queue);
+ espi->current_msg = msg;
+ spin_unlock_irq(&espi->lock);
+
+ ep93xx_spi_process_message(espi, msg);
+
+ /*
+ * Update the current message and re-schedule ourselves if there are
+ * more messages in the queue.
+ */
+ spin_lock_irq(&espi->lock);
+ espi->current_msg = NULL;
+ if (espi->running && !list_empty(&espi->msg_queue))
+ queue_work(espi->wq, &espi->msg_work);
+ spin_unlock_irq(&espi->lock);
+
+ /* notify the protocol driver that we are done with this message */
+ msg->complete(msg->context);
+}
+
+static irqreturn_t ep93xx_spi_interrupt(int irq, void *dev_id)
+{
+ struct ep93xx_spi *espi = dev_id;
+ u8 irq_status = ep93xx_spi_read_u8(espi, SSPIIR);
+
+ /*
+ * If we got ROR (receive overrun) interrupt we know that something is
+ * wrong. Just abort the message.
+ */
+ if (unlikely(irq_status & SSPIIR_RORIS)) {
+ /* clear the overrun interrupt */
+ ep93xx_spi_write_u8(espi, SSPICR, 0);
+ dev_warn(&espi->pdev->dev,
+ "receive overrun, aborting the message\n");
+ espi->current_msg->status = -EIO;
+ } else {
+ /*
+ * Interrupt is either RX (RIS) or TX (TIS). For both cases we
+ * simply execute next data transfer.
+ */
+ if (ep93xx_spi_read_write(espi)) {
+ /*
+ * In normal case, there still is some processing left
+ * for current transfer. Let's wait for the next
+ * interrupt then.
+ */
+ return IRQ_HANDLED;
+ }
+ }
+
+ /*
+ * Current transfer is finished, either with error or with success. In
+ * any case we disable interrupts and notify the worker to handle
+ * any post-processing of the message.
+ */
+ ep93xx_spi_disable_interrupts(espi);
+ complete(&espi->wait);
+ return IRQ_HANDLED;
+}
+
+static int __init ep93xx_spi_probe(struct platform_device *pdev)
+{
+ struct spi_master *master;
+ struct ep93xx_spi_info *info;
+ struct ep93xx_spi *espi;
+ struct resource *res;
+ int error;
+
+ info = pdev->dev.platform_data;
+
+ master = spi_alloc_master(&pdev->dev, sizeof(*espi));
+ if (!master) {
+ dev_err(&pdev->dev, "failed to allocate spi master\n");
+ return -ENOMEM;
+ }
+
+ master->setup = ep93xx_spi_setup;
+ master->transfer = ep93xx_spi_transfer;
+ master->cleanup = ep93xx_spi_cleanup;
+ master->bus_num = pdev->id;
+ master->num_chipselect = info->num_chipselect;
+ master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+
+ platform_set_drvdata(pdev, master);
+
+ espi = spi_master_get_devdata(master);
+
+ espi->clk = clk_get(&pdev->dev, NULL);
+ if (IS_ERR(espi->clk)) {
+ dev_err(&pdev->dev, "unable to get spi clock\n");
+ error = PTR_ERR(espi->clk);
+ goto fail_release_master;
+ }
+
+ spin_lock_init(&espi->lock);
+ init_completion(&espi->wait);
+
+ /*
+ * Calculate maximum and minimum supported clock rates
+ * for the controller.
+ */
+ espi->max_rate = clk_get_rate(espi->clk) / 2;
+ espi->min_rate = clk_get_rate(espi->clk) / (254 * 256);
+ espi->pdev = pdev;
+
+ espi->irq = platform_get_irq(pdev, 0);
+ if (espi->irq < 0) {
+ error = -EBUSY;
+ dev_err(&pdev->dev, "failed to get irq resources\n");
+ goto fail_put_clock;
+ }
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res) {
+ dev_err(&pdev->dev, "unable to get iomem resource\n");
+ error = -ENODEV;
+ goto fail_put_clock;
+ }
+
+ res = request_mem_region(res->start, resource_size(res), pdev->name);
+ if (!res) {
+ dev_err(&pdev->dev, "unable to request iomem resources\n");
+ error = -EBUSY;
+ goto fail_put_clock;
+ }
+
+ espi->regs_base = ioremap(res->start, resource_size(res));
+ if (!espi->regs_base) {
+ dev_err(&pdev->dev, "failed to map resources\n");
+ error = -ENODEV;
+ goto fail_free_mem;
+ }
+
+ error = request_irq(espi->irq, ep93xx_spi_interrupt, 0,
+ "ep93xx-spi", espi);
+ if (error) {
+ dev_err(&pdev->dev, "failed to request irq\n");
+ goto fail_unmap_regs;
+ }
+
+ espi->wq = create_singlethread_workqueue("ep93xx_spid");
+ if (!espi->wq) {
+ dev_err(&pdev->dev, "unable to create workqueue\n");
+ goto fail_free_irq;
+ }
+ INIT_WORK(&espi->msg_work, ep93xx_spi_work);
+ INIT_LIST_HEAD(&espi->msg_queue);
+ espi->running = true;
+
+ /* make sure that the hardware is disabled */
+ ep93xx_spi_write_u8(espi, SSPCR1, 0);
+
+ error = spi_register_master(master);
+ if (error) {
+ dev_err(&pdev->dev, "failed to register SPI master\n");
+ goto fail_free_queue;
+ }
+
+ dev_info(&pdev->dev, "EP93xx SPI Controller at 0x%08lx irq %d\n",
+ (unsigned long)res->start, espi->irq);
+
+ return 0;
+
+fail_free_queue:
+ destroy_workqueue(espi->wq);
+fail_free_irq:
+ free_irq(espi->irq, espi);
+fail_unmap_regs:
+ iounmap(espi->regs_base);
+fail_free_mem:
+ release_mem_region(res->start, resource_size(res));
+fail_put_clock:
+ clk_put(espi->clk);
+fail_release_master:
+ spi_master_put(master);
+ platform_set_drvdata(pdev, NULL);
+
+ return error;
+}
+
+static int __exit ep93xx_spi_remove(struct platform_device *pdev)
+{
+ struct spi_master *master = platform_get_drvdata(pdev);
+ struct ep93xx_spi *espi = spi_master_get_devdata(master);
+ struct resource *res;
+
+ spin_lock_irq(&espi->lock);
+ espi->running = false;
+ spin_unlock_irq(&espi->lock);
+
+ destroy_workqueue(espi->wq);
+
+ /*
+ * Complete remaining messages with %-ESHUTDOWN status.
+ */
+ spin_lock_irq(&espi->lock);
+ while (!list_empty(&espi->msg_queue)) {
+ struct spi_message *msg;
+
+ msg = list_first_entry(&espi->msg_queue,
+ struct spi_message, queue);
+ list_del_init(&msg->queue);
+ msg->status = -ESHUTDOWN;
+ spin_unlock_irq(&espi->lock);
+ msg->complete(msg->context);
+ spin_lock_irq(&espi->lock);
+ }
+ spin_unlock_irq(&espi->lock);
+
+ free_irq(espi->irq, espi);
+ iounmap(espi->regs_base);
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ release_mem_region(res->start, resource_size(res));
+ clk_put(espi->clk);
+ platform_set_drvdata(pdev, NULL);
+
+ spi_unregister_master(master);
+ return 0;
+}
+
+static struct platform_driver ep93xx_spi_driver = {
+ .driver = {
+ .name = "ep93xx-spi",
+ .owner = THIS_MODULE,
+ },
+ .remove = __exit_p(ep93xx_spi_remove),
+};
+
+static int __init ep93xx_spi_init(void)
+{
+ return platform_driver_probe(&ep93xx_spi_driver, ep93xx_spi_probe);
+}
+module_init(ep93xx_spi_init);
+
+static void __exit ep93xx_spi_exit(void)
+{
+ platform_driver_unregister(&ep93xx_spi_driver);
+}
+module_exit(ep93xx_spi_exit);
+
+MODULE_DESCRIPTION("EP93xx SPI Controller driver");
+MODULE_AUTHOR("Mika Westerberg <mika.westerberg at iki.fi>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ep93xx-spi");
--
1.5.6.5
More information about the linux-arm-kernel
mailing list