From 9e862375c5420a329521c458a3c808c127e9038f Mon Sep 17 00:00:00 2001 From: Lee Jones Date: Tue, 9 Dec 2014 20:21:30 +0000 Subject: spi: Add new driver for STMicroelectronics' SPI Controller This patch adds support for the SPI portion of ST's SSC device. Signed-off-by: Lee Jones Signed-off-by: Mark Brown --- drivers/spi/spi-st-ssc4.c | 510 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 510 insertions(+) create mode 100644 drivers/spi/spi-st-ssc4.c (limited to 'drivers/spi/spi-st-ssc4.c') diff --git a/drivers/spi/spi-st-ssc4.c b/drivers/spi/spi-st-ssc4.c new file mode 100644 index 000000000000..8f8770a97ba7 --- /dev/null +++ b/drivers/spi/spi-st-ssc4.c @@ -0,0 +1,510 @@ +/* + * Copyright (c) 2008-2014 STMicroelectronics Limited + * + * Author: Angus Clark + * Patrice Chotard + * Lee Jones + * + * SPI master mode controller driver, used in STMicroelectronics devices. + * + * May be copied or modified under the terms of the GNU General Public + * License Version 2.0 only. See linux/COPYING for more information. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* SSC registers */ +#define SSC_BRG 0x000 +#define SSC_TBUF 0x004 +#define SSC_RBUF 0x008 +#define SSC_CTL 0x00C +#define SSC_IEN 0x010 +#define SSC_I2C 0x018 + +/* SSC Control */ +#define SSC_CTL_DATA_WIDTH_9 0x8 +#define SSC_CTL_DATA_WIDTH_MSK 0xf +#define SSC_CTL_BM 0xf +#define SSC_CTL_HB BIT(4) +#define SSC_CTL_PH BIT(5) +#define SSC_CTL_PO BIT(6) +#define SSC_CTL_SR BIT(7) +#define SSC_CTL_MS BIT(8) +#define SSC_CTL_EN BIT(9) +#define SSC_CTL_LPB BIT(10) +#define SSC_CTL_EN_TX_FIFO BIT(11) +#define SSC_CTL_EN_RX_FIFO BIT(12) +#define SSC_CTL_EN_CLST_RX BIT(13) + +/* SSC Interrupt Enable */ +#define SSC_IEN_TEEN BIT(2) + +#define FIFO_SIZE 8 + +struct spi_st { + /* SSC SPI Controller */ + void __iomem *base; + struct clk *clk; + struct device *dev; + + /* SSC SPI current transaction */ + const u8 *tx_ptr; + u8 *rx_ptr; + u16 bytes_per_word; + unsigned int words_remaining; + unsigned int baud; + struct completion done; +}; + +static int spi_st_clk_enable(struct spi_st *spi_st) +{ + /* + * Current platforms use one of the core clocks for SPI and I2C. + * If we attempt to disable the clock, the system will hang. + * + * TODO: Remove this when platform supports power domains. + */ + return 0; + + return clk_prepare_enable(spi_st->clk); +} + +static void spi_st_clk_disable(struct spi_st *spi_st) +{ + /* + * Current platforms use one of the core clocks for SPI and I2C. + * If we attempt to disable the clock, the system will hang. + * + * TODO: Remove this when platform supports power domains. + */ + return; + + clk_disable_unprepare(spi_st->clk); +} + +/* Load the TX FIFO */ +static void ssc_write_tx_fifo(struct spi_st *spi_st) +{ + unsigned int count, i; + uint32_t word = 0; + + if (spi_st->words_remaining > FIFO_SIZE) + count = FIFO_SIZE; + else + count = spi_st->words_remaining; + + for (i = 0; i < count; i++) { + if (spi_st->tx_ptr) { + if (spi_st->bytes_per_word == 1) { + word = *spi_st->tx_ptr++; + } else { + word = *spi_st->tx_ptr++; + word = *spi_st->tx_ptr++ | (word << 8); + } + } + writel_relaxed(word, spi_st->base + SSC_TBUF); + } +} + +/* Read the RX FIFO */ +static void ssc_read_rx_fifo(struct spi_st *spi_st) +{ + unsigned int count, i; + uint32_t word = 0; + + if (spi_st->words_remaining > FIFO_SIZE) + count = FIFO_SIZE; + else + count = spi_st->words_remaining; + + for (i = 0; i < count; i++) { + word = readl_relaxed(spi_st->base + SSC_RBUF); + + if (spi_st->rx_ptr) { + if (spi_st->bytes_per_word == 1) { + *spi_st->rx_ptr++ = (uint8_t)word; + } else { + *spi_st->rx_ptr++ = (word >> 8); + *spi_st->rx_ptr++ = word & 0xff; + } + } + } + spi_st->words_remaining -= count; +} + +static int spi_st_transfer_one(struct spi_master *master, + struct spi_device *spi, struct spi_transfer *t) +{ + struct spi_st *spi_st = spi_master_get_devdata(master); + uint32_t ctl = 0; + + /* Setup transfer */ + spi_st->tx_ptr = t->tx_buf; + spi_st->rx_ptr = t->rx_buf; + + if (spi->bits_per_word > 8) { + /* + * Anything greater than 8 bits-per-word requires 2 + * bytes-per-word in the RX/TX buffers + */ + spi_st->bytes_per_word = 2; + spi_st->words_remaining = t->len / 2; + + } else if (spi->bits_per_word == 8 && !(t->len & 0x1)) { + /* + * If transfer is even-length, and 8 bits-per-word, then + * implement as half-length 16 bits-per-word transfer + */ + spi_st->bytes_per_word = 2; + spi_st->words_remaining = t->len / 2; + + /* Set SSC_CTL to 16 bits-per-word */ + ctl = readl_relaxed(spi_st->base + SSC_CTL); + writel_relaxed((ctl | 0xf), spi_st->base + SSC_CTL); + + readl_relaxed(spi_st->base + SSC_RBUF); + + } else { + spi_st->bytes_per_word = 1; + spi_st->words_remaining = t->len; + } + + reinit_completion(&spi_st->done); + + /* Start transfer by writing to the TX FIFO */ + ssc_write_tx_fifo(spi_st); + writel_relaxed(SSC_IEN_TEEN, spi_st->base + SSC_IEN); + + /* Wait for transfer to complete */ + wait_for_completion(&spi_st->done); + + /* Restore SSC_CTL if necessary */ + if (ctl) + writel_relaxed(ctl, spi_st->base + SSC_CTL); + + spi_finalize_current_transfer(spi->master); + + return t->len; +} + +static void spi_st_cleanup(struct spi_device *spi) +{ + int cs = spi->cs_gpio; + + if (gpio_is_valid(cs)) + devm_gpio_free(&spi->dev, cs); +} + +/* the spi->mode bits understood by this driver: */ +#define MODEBITS (SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_LOOP | SPI_CS_HIGH) +static int spi_st_setup(struct spi_device *spi) +{ + struct spi_st *spi_st = spi_master_get_devdata(spi->master); + u32 spi_st_clk, sscbrg, var; + u32 hz = spi->max_speed_hz; + int cs = spi->cs_gpio; + int ret; + + if (spi->mode & ~MODEBITS) { + dev_err(&spi->dev, "unsupported mode bits 0x%x\n", + spi->mode & ~MODEBITS); + return -EINVAL; + } + + if (!hz) { + dev_err(&spi->dev, "max_speed_hz unspecified\n"); + return -EINVAL; + } + + if (!gpio_is_valid(cs)) { + dev_err(&spi->dev, "%d is not a valid gpio\n", cs); + return -EINVAL; + } + + if (devm_gpio_request(&spi->dev, cs, dev_name(&spi->dev))) { + dev_err(&spi->dev, "could not request gpio:%d\n", cs); + return -EINVAL; + } + + ret = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH); + if (ret) + return ret; + + spi_st_clk = clk_get_rate(spi_st->clk); + + /* Set SSC_BRF */ + sscbrg = spi_st_clk / (2 * hz); + if (sscbrg < 0x07 || sscbrg > BIT(16)) { + dev_err(&spi->dev, + "baudrate %d outside valid range %d\n", sscbrg, hz); + return -EINVAL; + } + + spi_st->baud = spi_st_clk / (2 * sscbrg); + if (sscbrg == BIT(16)) /* 16-bit counter wraps */ + sscbrg = 0x0; + + writel_relaxed(sscbrg, spi_st->base + SSC_BRG); + + dev_dbg(&spi->dev, + "setting baudrate:target= %u hz, actual= %u hz, sscbrg= %u\n", + hz, spi_st->baud, sscbrg); + + /* Set SSC_CTL and enable SSC */ + var = readl_relaxed(spi_st->base + SSC_CTL); + var |= SSC_CTL_MS; + + if (spi->mode & SPI_CPOL) + var |= SSC_CTL_PO; + else + var &= ~SSC_CTL_PO; + + if (spi->mode & SPI_CPHA) + var |= SSC_CTL_PH; + else + var &= ~SSC_CTL_PH; + + if ((spi->mode & SPI_LSB_FIRST) == 0) + var |= SSC_CTL_HB; + else + var &= ~SSC_CTL_HB; + + if (spi->mode & SPI_LOOP) + var |= SSC_CTL_LPB; + else + var &= ~SSC_CTL_LPB; + + var &= ~SSC_CTL_DATA_WIDTH_MSK; + var |= (spi->bits_per_word - 1); + + var |= SSC_CTL_EN_TX_FIFO | SSC_CTL_EN_RX_FIFO; + var |= SSC_CTL_EN; + + writel_relaxed(var, spi_st->base + SSC_CTL); + + /* Clear the status register */ + readl_relaxed(spi_st->base + SSC_RBUF); + + return 0; +} + +/* Interrupt fired when TX shift register becomes empty */ +static irqreturn_t spi_st_irq(int irq, void *dev_id) +{ + struct spi_st *spi_st = (struct spi_st *)dev_id; + + /* Read RX FIFO */ + ssc_read_rx_fifo(spi_st); + + /* Fill TX FIFO */ + if (spi_st->words_remaining) { + ssc_write_tx_fifo(spi_st); + } else { + /* TX/RX complete */ + writel_relaxed(0x0, spi_st->base + SSC_IEN); + /* + * read SSC_IEN to ensure that this bit is set + * before re-enabling interrupt + */ + readl(spi_st->base + SSC_IEN); + complete(&spi_st->done); + } + + return IRQ_HANDLED; +} + +static int spi_st_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct spi_master *master; + struct resource *res; + struct spi_st *spi_st; + int irq, ret = 0; + u32 var; + + master = spi_alloc_master(&pdev->dev, sizeof(*spi_st)); + if (!master) + return -ENOMEM; + + master->dev.of_node = np; + master->mode_bits = MODEBITS; + master->setup = spi_st_setup; + master->cleanup = spi_st_cleanup; + master->transfer_one = spi_st_transfer_one; + master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16); + master->auto_runtime_pm = true; + master->bus_num = pdev->id; + spi_st = spi_master_get_devdata(master); + + spi_st->clk = devm_clk_get(&pdev->dev, "ssc"); + if (IS_ERR(spi_st->clk)) { + dev_err(&pdev->dev, "Unable to request clock\n"); + return PTR_ERR(spi_st->clk); + } + + ret = spi_st_clk_enable(spi_st); + if (ret) + return ret; + + init_completion(&spi_st->done); + + /* Get resources */ + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + spi_st->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(spi_st->base)) { + ret = PTR_ERR(spi_st->base); + goto clk_disable; + } + + /* Disable I2C and Reset SSC */ + writel_relaxed(0x0, spi_st->base + SSC_I2C); + var = readw_relaxed(spi_st->base + SSC_CTL); + var |= SSC_CTL_SR; + writel_relaxed(var, spi_st->base + SSC_CTL); + + udelay(1); + var = readl_relaxed(spi_st->base + SSC_CTL); + var &= ~SSC_CTL_SR; + writel_relaxed(var, spi_st->base + SSC_CTL); + + /* Set SSC into slave mode before reconfiguring PIO pins */ + var = readl_relaxed(spi_st->base + SSC_CTL); + var &= ~SSC_CTL_MS; + writel_relaxed(var, spi_st->base + SSC_CTL); + + irq = irq_of_parse_and_map(np, 0); + if (!irq) { + dev_err(&pdev->dev, "IRQ missing or invalid\n"); + ret = -EINVAL; + goto clk_disable; + } + + ret = devm_request_irq(&pdev->dev, irq, spi_st_irq, 0, + pdev->name, spi_st); + if (ret) { + dev_err(&pdev->dev, "Failed to request irq %d\n", irq); + goto clk_disable; + } + + /* by default the device is on */ + pm_runtime_set_active(&pdev->dev); + pm_runtime_enable(&pdev->dev); + + platform_set_drvdata(pdev, master); + + ret = devm_spi_register_master(&pdev->dev, master); + if (ret) { + dev_err(&pdev->dev, "Failed to register master\n"); + goto clk_disable; + } + + return 0; + +clk_disable: + spi_st_clk_disable(spi_st); + + return ret; +} + +static int spi_st_remove(struct platform_device *pdev) +{ + struct spi_master *master = platform_get_drvdata(pdev); + struct spi_st *spi_st = spi_master_get_devdata(master); + + spi_st_clk_disable(spi_st); + + pinctrl_pm_select_sleep_state(&pdev->dev); + + return 0; +} + +#ifdef CONFIG_PM +static int spi_st_runtime_suspend(struct device *dev) +{ + struct spi_master *master = dev_get_drvdata(dev); + struct spi_st *spi_st = spi_master_get_devdata(master); + + writel_relaxed(0, spi_st->base + SSC_IEN); + pinctrl_pm_select_sleep_state(dev); + + spi_st_clk_disable(spi_st); + + return 0; +} + +static int spi_st_runtime_resume(struct device *dev) +{ + struct spi_master *master = dev_get_drvdata(dev); + struct spi_st *spi_st = spi_master_get_devdata(master); + int ret; + + ret = spi_st_clk_enable(spi_st); + pinctrl_pm_select_default_state(dev); + + return ret; +} +#endif + +#ifdef CONFIG_PM_SLEEP +static int spi_st_suspend(struct device *dev) +{ + struct spi_master *master = dev_get_drvdata(dev); + int ret; + + ret = spi_master_suspend(master); + if (ret) + return ret; + + return pm_runtime_force_suspend(dev); +} + +static int spi_st_resume(struct device *dev) +{ + struct spi_master *master = dev_get_drvdata(dev); + int ret; + + ret = spi_master_resume(master); + if (ret) + return ret; + + return pm_runtime_force_resume(dev); +} +#endif + +static const struct dev_pm_ops spi_st_pm = { + SET_SYSTEM_SLEEP_PM_OPS(spi_st_suspend, spi_st_resume) + SET_RUNTIME_PM_OPS(spi_st_runtime_suspend, spi_st_runtime_resume, NULL) +}; + +static struct of_device_id stm_spi_match[] = { + { .compatible = "st,comms-ssc4-spi", }, + {}, +}; +MODULE_DEVICE_TABLE(of, stm_spi_match); + +static struct platform_driver spi_st_driver = { + .driver = { + .name = "spi-st", + .pm = &spi_st_pm, + .of_match_table = of_match_ptr(stm_spi_match), + }, + .probe = spi_st_probe, + .remove = spi_st_remove, +}; +module_platform_driver(spi_st_driver); + +MODULE_AUTHOR("Patrice Chotard "); +MODULE_DESCRIPTION("STM SSC SPI driver"); +MODULE_LICENSE("GPL v2"); -- cgit v1.2.3