diff options
Diffstat (limited to 'drivers/spi/xilinx_spi.c')
| -rw-r--r-- | drivers/spi/xilinx_spi.c | 434 |
1 files changed, 434 insertions, 0 deletions
diff --git a/drivers/spi/xilinx_spi.c b/drivers/spi/xilinx_spi.c new file mode 100644 index 00000000000..f0bf9a68e96 --- /dev/null +++ b/drivers/spi/xilinx_spi.c @@ -0,0 +1,434 @@ +/* + * xilinx_spi.c + * + * Xilinx SPI controller driver (master mode only) + * + * Author: MontaVista Software, Inc. + * source@mvista.com + * + * 2002-2007 (c) MontaVista Software, Inc. This file is licensed under the + * terms of the GNU General Public License version 2. This program is licensed + * "as is" without any warranty of any kind, whether express or implied. + */ + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/platform_device.h> +#include <linux/spi/spi.h> +#include <linux/spi/spi_bitbang.h> +#include <linux/io.h> + +#include <syslib/virtex_devices.h> + +#define XILINX_SPI_NAME "xspi" + +/* Register definitions as per "OPB Serial Peripheral Interface (SPI) (v1.00e) + * Product Specification", DS464 + */ +#define XSPI_CR_OFFSET 0x62 /* 16-bit Control Register */ + +#define XSPI_CR_ENABLE 0x02 +#define XSPI_CR_MASTER_MODE 0x04 +#define XSPI_CR_CPOL 0x08 +#define XSPI_CR_CPHA 0x10 +#define XSPI_CR_MODE_MASK (XSPI_CR_CPHA | XSPI_CR_CPOL) +#define XSPI_CR_TXFIFO_RESET 0x20 +#define XSPI_CR_RXFIFO_RESET 0x40 +#define XSPI_CR_MANUAL_SSELECT 0x80 +#define XSPI_CR_TRANS_INHIBIT 0x100 + +#define XSPI_SR_OFFSET 0x67 /* 8-bit Status Register */ + +#define XSPI_SR_RX_EMPTY_MASK 0x01 /* Receive FIFO is empty */ +#define XSPI_SR_RX_FULL_MASK 0x02 /* Receive FIFO is full */ +#define XSPI_SR_TX_EMPTY_MASK 0x04 /* Transmit FIFO is empty */ +#define XSPI_SR_TX_FULL_MASK 0x08 /* Transmit FIFO is full */ +#define XSPI_SR_MODE_FAULT_MASK 0x10 /* Mode fault error */ + +#define XSPI_TXD_OFFSET 0x6b /* 8-bit Data Transmit Register */ +#define XSPI_RXD_OFFSET 0x6f /* 8-bit Data Receive Register */ + +#define XSPI_SSR_OFFSET 0x70 /* 32-bit Slave Select Register */ + +/* Register definitions as per "OPB IPIF (v3.01c) Product Specification", DS414 + * IPIF registers are 32 bit + */ +#define XIPIF_V123B_DGIER_OFFSET 0x1c /* IPIF global int enable reg */ +#define XIPIF_V123B_GINTR_ENABLE 0x80000000 + +#define XIPIF_V123B_IISR_OFFSET 0x20 /* IPIF interrupt status reg */ +#define XIPIF_V123B_IIER_OFFSET 0x28 /* IPIF interrupt enable reg */ + +#define XSPI_INTR_MODE_FAULT 0x01 /* Mode fault error */ +#define XSPI_INTR_SLAVE_MODE_FAULT 0x02 /* Selected as slave while + * disabled */ +#define XSPI_INTR_TX_EMPTY 0x04 /* TxFIFO is empty */ +#define XSPI_INTR_TX_UNDERRUN 0x08 /* TxFIFO was underrun */ +#define XSPI_INTR_RX_FULL 0x10 /* RxFIFO is full */ +#define XSPI_INTR_RX_OVERRUN 0x20 /* RxFIFO was overrun */ + +#define XIPIF_V123B_RESETR_OFFSET 0x40 /* IPIF reset register */ +#define XIPIF_V123B_RESET_MASK 0x0a /* the value to write */ + +struct xilinx_spi { + /* bitbang has to be first */ + struct spi_bitbang bitbang; + struct completion done; + + void __iomem *regs; /* virt. address of the control registers */ + + u32 irq; + + u32 speed_hz; /* SCK has a fixed frequency of speed_hz Hz */ + + u8 *rx_ptr; /* pointer in the Tx buffer */ + const u8 *tx_ptr; /* pointer in the Rx buffer */ + int remaining_bytes; /* the number of bytes left to transfer */ +}; + +static void xspi_init_hw(void __iomem *regs_base) +{ + /* Reset the SPI device */ + out_be32(regs_base + XIPIF_V123B_RESETR_OFFSET, + XIPIF_V123B_RESET_MASK); + /* Disable all the interrupts just in case */ + out_be32(regs_base + XIPIF_V123B_IIER_OFFSET, 0); + /* Enable the global IPIF interrupt */ + out_be32(regs_base + XIPIF_V123B_DGIER_OFFSET, + XIPIF_V123B_GINTR_ENABLE); + /* Deselect the slave on the SPI bus */ + out_be32(regs_base + XSPI_SSR_OFFSET, 0xffff); + /* Disable the transmitter, enable Manual Slave Select Assertion, + * put SPI controller into master mode, and enable it */ + out_be16(regs_base + XSPI_CR_OFFSET, + XSPI_CR_TRANS_INHIBIT | XSPI_CR_MANUAL_SSELECT + | XSPI_CR_MASTER_MODE | XSPI_CR_ENABLE); +} + +static void xilinx_spi_chipselect(struct spi_device *spi, int is_on) +{ + struct xilinx_spi *xspi = spi_master_get_devdata(spi->master); + + if (is_on == BITBANG_CS_INACTIVE) { + /* Deselect the slave on the SPI bus */ + out_be32(xspi->regs + XSPI_SSR_OFFSET, 0xffff); + } else if (is_on == BITBANG_CS_ACTIVE) { + /* Set the SPI clock phase and polarity */ + u16 cr = in_be16(xspi->regs + XSPI_CR_OFFSET) + & ~XSPI_CR_MODE_MASK; + if (spi->mode & SPI_CPHA) + cr |= XSPI_CR_CPHA; + if (spi->mode & SPI_CPOL) + cr |= XSPI_CR_CPOL; + out_be16(xspi->regs + XSPI_CR_OFFSET, cr); + + /* We do not check spi->max_speed_hz here as the SPI clock + * frequency is not software programmable (the IP block design + * parameter) + */ + + /* Activate the chip select */ + out_be32(xspi->regs + XSPI_SSR_OFFSET, + ~(0x0001 << spi->chip_select)); + } +} + +/* spi_bitbang requires custom setup_transfer() to be defined if there is a + * custom txrx_bufs(). We have nothing to setup here as the SPI IP block + * supports just 8 bits per word, and SPI clock can't be changed in software. + * Check for 8 bits per word. Chip select delay calculations could be + * added here as soon as bitbang_work() can be made aware of the delay value. + */ +static int xilinx_spi_setup_transfer(struct spi_device *spi, + struct spi_transfer *t) +{ + u8 bits_per_word; + u32 hz; + struct xilinx_spi *xspi = spi_master_get_devdata(spi->master); + + bits_per_word = (t) ? t->bits_per_word : spi->bits_per_word; + hz = (t) ? t->speed_hz : spi->max_speed_hz; + if (bits_per_word != 8) { + dev_err(&spi->dev, "%s, unsupported bits_per_word=%d\n", + __FUNCTION__, bits_per_word); + return -EINVAL; + } + + if (hz && xspi->speed_hz > hz) { + dev_err(&spi->dev, "%s, unsupported clock rate %uHz\n", + __FUNCTION__, hz); + return -EINVAL; + } + + return 0; +} + +/* the spi->mode bits understood by this driver: */ +#define MODEBITS (SPI_CPOL | SPI_CPHA) + +static int xilinx_spi_setup(struct spi_device *spi) +{ + struct spi_bitbang *bitbang; + struct xilinx_spi *xspi; + int retval; + + xspi = spi_master_get_devdata(spi->master); + bitbang = &xspi->bitbang; + + if (!spi->bits_per_word) + spi->bits_per_word = 8; + + if (spi->mode & ~MODEBITS) { + dev_err(&spi->dev, "%s, unsupported mode bits %x\n", + __FUNCTION__, spi->mode & ~MODEBITS); + return -EINVAL; + } + + retval = xilinx_spi_setup_transfer(spi, NULL); + if (retval < 0) + return retval; + + dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec/bit\n", + __FUNCTION__, spi->mode & MODEBITS, spi->bits_per_word, 0); + + return 0; +} + +static void xilinx_spi_fill_tx_fifo(struct xilinx_spi *xspi) +{ + u8 sr; + + /* Fill the Tx FIFO with as many bytes as possible */ + sr = in_8(xspi->regs + XSPI_SR_OFFSET); + while ((sr & XSPI_SR_TX_FULL_MASK) == 0 && xspi->remaining_bytes > 0) { + if (xspi->tx_ptr) { + out_8(xspi->regs + XSPI_TXD_OFFSET, *xspi->tx_ptr++); + } else { + out_8(xspi->regs + XSPI_TXD_OFFSET, 0); + } + xspi->remaining_bytes--; + sr = in_8(xspi->regs + XSPI_SR_OFFSET); + } +} + +static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t) +{ + struct xilinx_spi *xspi = spi_master_get_devdata(spi->master); + u32 ipif_ier; + u16 cr; + + /* We get here with transmitter inhibited */ + + xspi->tx_ptr = t->tx_buf; + xspi->rx_ptr = t->rx_buf; + xspi->remaining_bytes = t->len; + INIT_COMPLETION(xspi->done); + + xilinx_spi_fill_tx_fifo(xspi); + + /* Enable the transmit empty interrupt, which we use to determine + * progress on the transmission. + */ + ipif_ier = in_be32(xspi->regs + XIPIF_V123B_IIER_OFFSET); + out_be32(xspi->regs + XIPIF_V123B_IIER_OFFSET, + ipif_ier | XSPI_INTR_TX_EMPTY); + + /* Start the transfer by not inhibiting the transmitter any longer */ + cr = in_be16(xspi->regs + XSPI_CR_OFFSET) & ~XSPI_CR_TRANS_INHIBIT; + out_be16(xspi->regs + XSPI_CR_OFFSET, cr); + + wait_for_completion(&xspi->done); + + /* Disable the transmit empty interrupt */ + out_be32(xspi->regs + XIPIF_V123B_IIER_OFFSET, ipif_ier); + + return t->len - xspi->remaining_bytes; +} + + +/* This driver supports single master mode only. Hence Tx FIFO Empty + * is the only interrupt we care about. + * Receive FIFO Overrun, Transmit FIFO Underrun, Mode Fault, and Slave Mode + * Fault are not to happen. + */ +static irqreturn_t xilinx_spi_irq(int irq, void *dev_id) +{ + struct xilinx_spi *xspi = dev_id; + u32 ipif_isr; + + /* Get the IPIF interrupts, and clear them immediately */ + ipif_isr = in_be32(xspi->regs + XIPIF_V123B_IISR_OFFSET); + out_be32(xspi->regs + XIPIF_V123B_IISR_OFFSET, ipif_isr); + + if (ipif_isr & XSPI_INTR_TX_EMPTY) { /* Transmission completed */ + u16 cr; + u8 sr; + + /* A transmit has just completed. Process received data and + * check for more data to transmit. Always inhibit the + * transmitter while the Isr refills the transmit register/FIFO, + * or make sure it is stopped if we're done. + */ + cr = in_be16(xspi->regs + XSPI_CR_OFFSET); + out_be16(xspi->regs + XSPI_CR_OFFSET, + cr | XSPI_CR_TRANS_INHIBIT); + + /* Read out all the data from the Rx FIFO */ + sr = in_8(xspi->regs + XSPI_SR_OFFSET); + while ((sr & XSPI_SR_RX_EMPTY_MASK) == 0) { + u8 data; + + data = in_8(xspi->regs + XSPI_RXD_OFFSET); + if (xspi->rx_ptr) { + *xspi->rx_ptr++ = data; + } + sr = in_8(xspi->regs + XSPI_SR_OFFSET); + } + + /* See if there is more data to send */ + if (xspi->remaining_bytes > 0) { + xilinx_spi_fill_tx_fifo(xspi); + /* Start the transfer by not inhibiting the + * transmitter any longer + */ + out_be16(xspi->regs + XSPI_CR_OFFSET, cr); + } else { + /* No more data to send. + * Indicate the transfer is completed. + */ + complete(&xspi->done); + } + } + + return IRQ_HANDLED; +} + +static int __init xilinx_spi_probe(struct platform_device *dev) +{ + int ret = 0; + struct spi_master *master; + struct xilinx_spi *xspi; + struct xspi_platform_data *pdata; + struct resource *r; + + /* Get resources(memory, IRQ) associated with the device */ + master = spi_alloc_master(&dev->dev, sizeof(struct xilinx_spi)); + + if (master == NULL) { + return -ENOMEM; + } + + platform_set_drvdata(dev, master); + pdata = dev->dev.platform_data; + + if (pdata == NULL) { + ret = -ENODEV; + goto put_master; + } + + r = platform_get_resource(dev, IORESOURCE_MEM, 0); + if (r == NULL) { + ret = -ENODEV; + goto put_master; + } + + xspi = spi_master_get_devdata(master); + xspi->bitbang.master = spi_master_get(master); + xspi->bitbang.chipselect = xilinx_spi_chipselect; + xspi->bitbang.setup_transfer = xilinx_spi_setup_transfer; + xspi->bitbang.txrx_bufs = xilinx_spi_txrx_bufs; + xspi->bitbang.master->setup = xilinx_spi_setup; + init_completion(&xspi->done); + + if (!request_mem_region(r->start, + r->end - r->start + 1, XILINX_SPI_NAME)) { + ret = -ENXIO; + goto put_master; + } + + xspi->regs = ioremap(r->start, r->end - r->start + 1); + if (xspi->regs == NULL) { + ret = -ENOMEM; + goto put_master; + } + + xspi->irq = platform_get_irq(dev, 0); + if (xspi->irq < 0) { + ret = -ENXIO; + goto unmap_io; + } + + master->bus_num = pdata->bus_num; + master->num_chipselect = pdata->num_chipselect; + xspi->speed_hz = pdata->speed_hz; + + /* SPI controller initializations */ + xspi_init_hw(xspi->regs); + + /* Register for SPI Interrupt */ + ret = request_irq(xspi->irq, xilinx_spi_irq, 0, XILINX_SPI_NAME, xspi); + if (ret != 0) + goto unmap_io; + + ret = spi_bitbang_start(&xspi->bitbang); + if (ret != 0) { + dev_err(&dev->dev, "spi_bitbang_start FAILED\n"); + goto free_irq; + } + + dev_info(&dev->dev, "at 0x%08X mapped to 0x%08X, irq=%d\n", + r->start, (u32)xspi->regs, xspi->irq); + + return ret; + +free_irq: + free_irq(xspi->irq, xspi); +unmap_io: + iounmap(xspi->regs); +put_master: + spi_master_put(master); + return ret; +} + +static int __devexit xilinx_spi_remove(struct platform_device *dev) +{ + struct xilinx_spi *xspi; + struct spi_master *master; + + master = platform_get_drvdata(dev); + xspi = spi_master_get_devdata(master); + + spi_bitbang_stop(&xspi->bitbang); + free_irq(xspi->irq, xspi); + iounmap(xspi->regs); + platform_set_drvdata(dev, 0); + spi_master_put(xspi->bitbang.master); + + return 0; +} + +static struct platform_driver xilinx_spi_driver = { + .probe = xilinx_spi_probe, + .remove = __devexit_p(xilinx_spi_remove), + .driver = { + .name = XILINX_SPI_NAME, + .owner = THIS_MODULE, + }, +}; + +static int __init xilinx_spi_init(void) +{ + return platform_driver_register(&xilinx_spi_driver); +} +module_init(xilinx_spi_init); + +static void __exit xilinx_spi_exit(void) +{ + platform_driver_unregister(&xilinx_spi_driver); +} +module_exit(xilinx_spi_exit); + +MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>"); +MODULE_DESCRIPTION("Xilinx SPI driver"); +MODULE_LICENSE("GPL"); |