/* * 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/of_platform.h> #include <linux/of_device.h> #include <linux/of_spi.h> #include <linux/spi/spi.h> #include <linux/spi/spi_bitbang.h> #include <linux/io.h> #define XILINX_SPI_NAME "xilinx_spi" /* 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; bits_per_word = (t) ? t->bits_per_word : spi->bits_per_word; if (bits_per_word != 8) { dev_err(&spi->dev, "%s, unsupported bits_per_word=%d\n", __func__, bits_per_word); 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", __func__, 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", __func__, 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_of_probe(struct of_device *ofdev, const struct of_device_id *match) { struct spi_master *master; struct xilinx_spi *xspi; struct resource r_irq_struct; struct resource r_mem_struct; struct resource *r_irq = &r_irq_struct; struct resource *r_mem = &r_mem_struct; int rc = 0; const u32 *prop; int len; /* Get resources(memory, IRQ) associated with the device */ master = spi_alloc_master(&ofdev->dev, sizeof(struct xilinx_spi)); if (master == NULL) { return -ENOMEM; } dev_set_drvdata(&ofdev->dev, master); rc = of_address_to_resource(ofdev->node, 0, r_mem); if (rc) { dev_warn(&ofdev->dev, "invalid address\n"); goto put_master; } rc = of_irq_to_resource(ofdev->node, 0, r_irq); if (rc == NO_IRQ) { dev_warn(&ofdev->dev, "no IRQ found\n"); 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); xspi->irq = r_irq->start; if (!request_mem_region(r_mem->start, r_mem->end - r_mem->start + 1, XILINX_SPI_NAME)) { rc = -ENXIO; dev_warn(&ofdev->dev, "memory request failure\n"); goto put_master; } xspi->regs = ioremap(r_mem->start, r_mem->end - r_mem->start + 1); if (xspi->regs == NULL) { rc = -ENOMEM; dev_warn(&ofdev->dev, "ioremap failure\n"); goto release_mem; } xspi->irq = r_irq->start; /* dynamic bus assignment */ master->bus_num = -1; /* number of slave select bits is required */ prop = of_get_property(ofdev->node, "xlnx,num-ss-bits", &len); if (!prop || len < sizeof(*prop)) { dev_warn(&ofdev->dev, "no 'xlnx,num-ss-bits' property\n"); goto unmap_io; } master->num_chipselect = *prop; /* SPI controller initializations */ xspi_init_hw(xspi->regs); /* Register for SPI Interrupt */ rc = request_irq(xspi->irq, xilinx_spi_irq, 0, XILINX_SPI_NAME, xspi); if (rc != 0) { dev_warn(&ofdev->dev, "irq request failure: %d\n", xspi->irq); goto unmap_io; } rc = spi_bitbang_start(&xspi->bitbang); if (rc != 0) { dev_err(&ofdev->dev, "spi_bitbang_start FAILED\n"); goto free_irq; } dev_info(&ofdev->dev, "at 0x%08X mapped to 0x%08X, irq=%d\n", (unsigned int)r_mem->start, (u32)xspi->regs, xspi->irq); /* Add any subnodes on the SPI bus */ of_register_spi_devices(master, ofdev->node); return rc; free_irq: free_irq(xspi->irq, xspi); unmap_io: iounmap(xspi->regs); release_mem: release_mem_region(r_mem->start, resource_size(r_mem)); put_master: spi_master_put(master); return rc; } static int __devexit xilinx_spi_remove(struct of_device *ofdev) { struct xilinx_spi *xspi; struct spi_master *master; struct resource r_mem; master = platform_get_drvdata(ofdev); xspi = spi_master_get_devdata(master); spi_bitbang_stop(&xspi->bitbang); free_irq(xspi->irq, xspi); iounmap(xspi->regs); if (!of_address_to_resource(ofdev->node, 0, &r_mem)) release_mem_region(r_mem.start, resource_size(&r_mem)); dev_set_drvdata(&ofdev->dev, 0); spi_master_put(xspi->bitbang.master); return 0; } /* work with hotplug and coldplug */ MODULE_ALIAS("platform:" XILINX_SPI_NAME); static int __exit xilinx_spi_of_remove(struct of_device *op) { return xilinx_spi_remove(op); } static struct of_device_id xilinx_spi_of_match[] = { { .compatible = "xlnx,xps-spi-2.00.a", }, { .compatible = "xlnx,xps-spi-2.00.b", }, {} }; MODULE_DEVICE_TABLE(of, xilinx_spi_of_match); static struct of_platform_driver xilinx_spi_of_driver = { .owner = THIS_MODULE, .name = "xilinx-xps-spi", .match_table = xilinx_spi_of_match, .probe = xilinx_spi_of_probe, .remove = __exit_p(xilinx_spi_of_remove), .driver = { .name = "xilinx-xps-spi", .owner = THIS_MODULE, }, }; static int __init xilinx_spi_init(void) { return of_register_platform_driver(&xilinx_spi_of_driver); } module_init(xilinx_spi_init); static void __exit xilinx_spi_exit(void) { of_unregister_platform_driver(&xilinx_spi_of_driver); } module_exit(xilinx_spi_exit); MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>"); MODULE_DESCRIPTION("Xilinx SPI driver"); MODULE_LICENSE("GPL");