/* * Xilinx SPI controller driver (master mode only) * * Author: MontaVista Software, Inc. * source@mvista.com * * Copyright (c) 2010 Secret Lab Technologies, Ltd. * Copyright (c) 2009 Intel Corporation * 2002-2007 (c) MontaVista Software, Inc. * 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/module.h> #include <linux/interrupt.h> #include <linux/of.h> #include <linux/platform_device.h> #include <linux/spi/spi.h> #include <linux/spi/spi_bitbang.h> #include <linux/spi/xilinx_spi.h> #include <linux/io.h> #define XILINX_SPI_MAX_CS 32 #define XILINX_SPI_NAME "xilinx_spi" /* Register definitions as per "OPB Serial Peripheral Interface (SPI) (v1.00e) * Product Specification", DS464 */ #define XSPI_CR_OFFSET 0x60 /* Control Register */ #define XSPI_CR_LOOP 0x01 #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 | \ XSPI_CR_LSB_FIRST | XSPI_CR_LOOP) #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_CR_LSB_FIRST 0x200 #define XSPI_SR_OFFSET 0x64 /* 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 0x68 /* Data Transmit Register */ #define XSPI_RXD_OFFSET 0x6c /* 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 XSPI_INTR_TX_HALF_EMPTY 0x40 /* TxFIFO is half empty */ #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 */ int irq; u8 *rx_ptr; /* pointer in the Tx buffer */ const u8 *tx_ptr; /* pointer in the Rx buffer */ u8 bytes_per_word; int buffer_size; /* buffer size in words */ u32 cs_inactive; /* Level of the CS pins when inactive*/ unsigned int (*read_fn)(void __iomem *); void (*write_fn)(u32, void __iomem *); }; static void xspi_write32(u32 val, void __iomem *addr) { iowrite32(val, addr); } static unsigned int xspi_read32(void __iomem *addr) { return ioread32(addr); } static void xspi_write32_be(u32 val, void __iomem *addr) { iowrite32be(val, addr); } static unsigned int xspi_read32_be(void __iomem *addr) { return ioread32be(addr); } static void xilinx_spi_tx(struct xilinx_spi *xspi) { u32 data = 0; if (!xspi->tx_ptr) { xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET); return; } switch (xspi->bytes_per_word) { case 1: data = *(u8 *)(xspi->tx_ptr); break; case 2: data = *(u16 *)(xspi->tx_ptr); break; case 4: data = *(u32 *)(xspi->tx_ptr); break; } xspi->write_fn(data, xspi->regs + XSPI_TXD_OFFSET); xspi->tx_ptr += xspi->bytes_per_word; } static void xilinx_spi_rx(struct xilinx_spi *xspi) { u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET); if (!xspi->rx_ptr) return; switch (xspi->bytes_per_word) { case 1: *(u8 *)(xspi->rx_ptr) = data; break; case 2: *(u16 *)(xspi->rx_ptr) = data; break; case 4: *(u32 *)(xspi->rx_ptr) = data; break; } xspi->rx_ptr += xspi->bytes_per_word; } static void xspi_init_hw(struct xilinx_spi *xspi) { void __iomem *regs_base = xspi->regs; /* Reset the SPI device */ xspi->write_fn(XIPIF_V123B_RESET_MASK, regs_base + XIPIF_V123B_RESETR_OFFSET); /* Enable the transmit empty interrupt, which we use to determine * progress on the transmission. */ xspi->write_fn(XSPI_INTR_TX_EMPTY, regs_base + XIPIF_V123B_IIER_OFFSET); /* Disable the global IPIF interrupt */ xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET); /* Deselect the slave on the SPI bus */ xspi->write_fn(0xffff, regs_base + XSPI_SSR_OFFSET); /* Disable the transmitter, enable Manual Slave Select Assertion, * put SPI controller into master mode, and enable it */ xspi->write_fn(XSPI_CR_MANUAL_SSELECT | XSPI_CR_MASTER_MODE | XSPI_CR_ENABLE | XSPI_CR_TXFIFO_RESET | XSPI_CR_RXFIFO_RESET, regs_base + XSPI_CR_OFFSET); } static void xilinx_spi_chipselect(struct spi_device *spi, int is_on) { struct xilinx_spi *xspi = spi_master_get_devdata(spi->master); u16 cr; u32 cs; if (is_on == BITBANG_CS_INACTIVE) { /* Deselect the slave on the SPI bus */ xspi->write_fn(xspi->cs_inactive, xspi->regs + XSPI_SSR_OFFSET); return; } /* Set the SPI clock phase and polarity */ cr = xspi->read_fn(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; if (spi->mode & SPI_LSB_FIRST) cr |= XSPI_CR_LSB_FIRST; if (spi->mode & SPI_LOOP) cr |= XSPI_CR_LOOP; xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET); /* We do not check spi->max_speed_hz here as the SPI clock * frequency is not software programmable (the IP block design * parameter) */ cs = xspi->cs_inactive; cs ^= BIT(spi->chip_select); /* Activate the chip select */ xspi->write_fn(cs, xspi->regs + XSPI_SSR_OFFSET); } /* spi_bitbang requires custom setup_transfer() to be defined if there is a * custom txrx_bufs(). */ static int xilinx_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t) { struct xilinx_spi *xspi = spi_master_get_devdata(spi->master); if (spi->mode & SPI_CS_HIGH) xspi->cs_inactive &= ~BIT(spi->chip_select); else xspi->cs_inactive |= BIT(spi->chip_select); return 0; } static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t) { struct xilinx_spi *xspi = spi_master_get_devdata(spi->master); int remaining_words; /* the number of words left to transfer */ bool use_irq = false; u16 cr = 0; /* We get here with transmitter inhibited */ xspi->tx_ptr = t->tx_buf; xspi->rx_ptr = t->rx_buf; remaining_words = t->len / xspi->bytes_per_word; reinit_completion(&xspi->done); if (xspi->irq >= 0 && remaining_words > xspi->buffer_size) { use_irq = true; xspi->write_fn(XSPI_INTR_TX_EMPTY, xspi->regs + XIPIF_V123B_IISR_OFFSET); /* Enable the global IPIF interrupt */ xspi->write_fn(XIPIF_V123B_GINTR_ENABLE, xspi->regs + XIPIF_V123B_DGIER_OFFSET); /* Inhibit irq to avoid spurious irqs on tx_empty*/ cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET); xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT, xspi->regs + XSPI_CR_OFFSET); } while (remaining_words) { int n_words, tx_words, rx_words; n_words = min(remaining_words, xspi->buffer_size); tx_words = n_words; while (tx_words--) xilinx_spi_tx(xspi); /* Start the transfer by not inhibiting the transmitter any * longer */ if (use_irq) { xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET); wait_for_completion(&xspi->done); } else while (!(xspi->read_fn(xspi->regs + XSPI_SR_OFFSET) & XSPI_SR_TX_EMPTY_MASK)) ; /* 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. */ if (use_irq) xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT, xspi->regs + XSPI_CR_OFFSET); /* Read out all the data from the Rx FIFO */ rx_words = n_words; while (rx_words--) xilinx_spi_rx(xspi); remaining_words -= n_words; } if (use_irq) xspi->write_fn(0, xspi->regs + XIPIF_V123B_DGIER_OFFSET); return t->len; } /* 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 = xspi->read_fn(xspi->regs + XIPIF_V123B_IISR_OFFSET); xspi->write_fn(ipif_isr, xspi->regs + XIPIF_V123B_IISR_OFFSET); if (ipif_isr & XSPI_INTR_TX_EMPTY) { /* Transmission completed */ complete(&xspi->done); } return IRQ_HANDLED; } static int xilinx_spi_find_buffer_size(struct xilinx_spi *xspi) { u8 sr; int n_words = 0; /* * Before the buffer_size detection we reset the core * to make sure we start with a clean state. */ xspi->write_fn(XIPIF_V123B_RESET_MASK, xspi->regs + XIPIF_V123B_RESETR_OFFSET); /* Fill the Tx FIFO with as many words as possible */ do { xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET); sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET); n_words++; } while (!(sr & XSPI_SR_TX_FULL_MASK)); return n_words; } static const 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 int xilinx_spi_probe(struct platform_device *pdev) { struct xilinx_spi *xspi; struct xspi_platform_data *pdata; struct resource *res; int ret, num_cs = 0, bits_per_word = 8; struct spi_master *master; u32 tmp; u8 i; pdata = dev_get_platdata(&pdev->dev); if (pdata) { num_cs = pdata->num_chipselect; bits_per_word = pdata->bits_per_word; } else { of_property_read_u32(pdev->dev.of_node, "xlnx,num-ss-bits", &num_cs); } if (!num_cs) { dev_err(&pdev->dev, "Missing slave select configuration data\n"); return -EINVAL; } if (num_cs > XILINX_SPI_MAX_CS) { dev_err(&pdev->dev, "Invalid number of spi slaves\n"); return -EINVAL; } master = spi_alloc_master(&pdev->dev, sizeof(struct xilinx_spi)); if (!master) return -ENODEV; /* the spi->mode bits understood by this driver: */ master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_LOOP | SPI_CS_HIGH; xspi = spi_master_get_devdata(master); xspi->cs_inactive = 0xffffffff; xspi->bitbang.master = master; xspi->bitbang.chipselect = xilinx_spi_chipselect; xspi->bitbang.setup_transfer = xilinx_spi_setup_transfer; xspi->bitbang.txrx_bufs = xilinx_spi_txrx_bufs; init_completion(&xspi->done); res = platform_get_resource(pdev, IORESOURCE_MEM, 0); xspi->regs = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(xspi->regs)) { ret = PTR_ERR(xspi->regs); goto put_master; } master->bus_num = pdev->id; master->num_chipselect = num_cs; master->dev.of_node = pdev->dev.of_node; /* * Detect endianess on the IP via loop bit in CR. Detection * must be done before reset is sent because incorrect reset * value generates error interrupt. * Setup little endian helper functions first and try to use them * and check if bit was correctly setup or not. */ xspi->read_fn = xspi_read32; xspi->write_fn = xspi_write32; xspi->write_fn(XSPI_CR_LOOP, xspi->regs + XSPI_CR_OFFSET); tmp = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET); tmp &= XSPI_CR_LOOP; if (tmp != XSPI_CR_LOOP) { xspi->read_fn = xspi_read32_be; xspi->write_fn = xspi_write32_be; } master->bits_per_word_mask = SPI_BPW_MASK(bits_per_word); xspi->bytes_per_word = bits_per_word / 8; xspi->buffer_size = xilinx_spi_find_buffer_size(xspi); xspi->irq = platform_get_irq(pdev, 0); if (xspi->irq >= 0) { /* Register for SPI Interrupt */ ret = devm_request_irq(&pdev->dev, xspi->irq, xilinx_spi_irq, 0, dev_name(&pdev->dev), xspi); if (ret) goto put_master; } /* SPI controller initializations */ xspi_init_hw(xspi); ret = spi_bitbang_start(&xspi->bitbang); if (ret) { dev_err(&pdev->dev, "spi_bitbang_start FAILED\n"); goto put_master; } dev_info(&pdev->dev, "at 0x%08llX mapped to 0x%p, irq=%d\n", (unsigned long long)res->start, xspi->regs, xspi->irq); if (pdata) { for (i = 0; i < pdata->num_devices; i++) spi_new_device(master, pdata->devices + i); } platform_set_drvdata(pdev, master); return 0; put_master: spi_master_put(master); return ret; } static int xilinx_spi_remove(struct platform_device *pdev) { struct spi_master *master = platform_get_drvdata(pdev); struct xilinx_spi *xspi = spi_master_get_devdata(master); void __iomem *regs_base = xspi->regs; spi_bitbang_stop(&xspi->bitbang); /* Disable all the interrupts just in case */ xspi->write_fn(0, regs_base + XIPIF_V123B_IIER_OFFSET); /* Disable the global IPIF interrupt */ xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET); spi_master_put(xspi->bitbang.master); return 0; } /* work with hotplug and coldplug */ MODULE_ALIAS("platform:" XILINX_SPI_NAME); static struct platform_driver xilinx_spi_driver = { .probe = xilinx_spi_probe, .remove = xilinx_spi_remove, .driver = { .name = XILINX_SPI_NAME, .of_match_table = xilinx_spi_of_match, }, }; module_platform_driver(xilinx_spi_driver); MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>"); MODULE_DESCRIPTION("Xilinx SPI driver"); MODULE_LICENSE("GPL");