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- // SPDX-License-Identifier: GPL-2.0
- //
- // Driver for AT91 USART Controllers as SPI
- //
- // Copyright (C) 2018 Microchip Technology Inc.
- //
- // Author: Radu Pirea <[email protected]>
- #include <linux/clk.h>
- #include <linux/delay.h>
- #include <linux/dmaengine.h>
- #include <linux/dma-direction.h>
- #include <linux/interrupt.h>
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <linux/of_platform.h>
- #include <linux/gpio/consumer.h>
- #include <linux/pinctrl/consumer.h>
- #include <linux/platform_device.h>
- #include <linux/pm_runtime.h>
- #include <linux/spi/spi.h>
- #define US_CR 0x00
- #define US_MR 0x04
- #define US_IER 0x08
- #define US_IDR 0x0C
- #define US_CSR 0x14
- #define US_RHR 0x18
- #define US_THR 0x1C
- #define US_BRGR 0x20
- #define US_VERSION 0xFC
- #define US_CR_RSTRX BIT(2)
- #define US_CR_RSTTX BIT(3)
- #define US_CR_RXEN BIT(4)
- #define US_CR_RXDIS BIT(5)
- #define US_CR_TXEN BIT(6)
- #define US_CR_TXDIS BIT(7)
- #define US_MR_SPI_MASTER 0x0E
- #define US_MR_CHRL GENMASK(7, 6)
- #define US_MR_CPHA BIT(8)
- #define US_MR_CPOL BIT(16)
- #define US_MR_CLKO BIT(18)
- #define US_MR_WRDBT BIT(20)
- #define US_MR_LOOP BIT(15)
- #define US_IR_RXRDY BIT(0)
- #define US_IR_TXRDY BIT(1)
- #define US_IR_OVRE BIT(5)
- #define US_BRGR_SIZE BIT(16)
- #define US_MIN_CLK_DIV 0x06
- #define US_MAX_CLK_DIV BIT(16)
- #define US_RESET (US_CR_RSTRX | US_CR_RSTTX)
- #define US_DISABLE (US_CR_RXDIS | US_CR_TXDIS)
- #define US_ENABLE (US_CR_RXEN | US_CR_TXEN)
- #define US_OVRE_RXRDY_IRQS (US_IR_OVRE | US_IR_RXRDY)
- #define US_INIT \
- (US_MR_SPI_MASTER | US_MR_CHRL | US_MR_CLKO | US_MR_WRDBT)
- #define US_DMA_MIN_BYTES 16
- #define US_DMA_TIMEOUT (msecs_to_jiffies(1000))
- /* Register access macros */
- #define at91_usart_spi_readl(port, reg) \
- readl_relaxed((port)->regs + US_##reg)
- #define at91_usart_spi_writel(port, reg, value) \
- writel_relaxed((value), (port)->regs + US_##reg)
- #define at91_usart_spi_readb(port, reg) \
- readb_relaxed((port)->regs + US_##reg)
- #define at91_usart_spi_writeb(port, reg, value) \
- writeb_relaxed((value), (port)->regs + US_##reg)
- struct at91_usart_spi {
- struct platform_device *mpdev;
- struct spi_transfer *current_transfer;
- void __iomem *regs;
- struct device *dev;
- struct clk *clk;
- struct completion xfer_completion;
- /*used in interrupt to protect data reading*/
- spinlock_t lock;
- phys_addr_t phybase;
- int irq;
- unsigned int current_tx_remaining_bytes;
- unsigned int current_rx_remaining_bytes;
- u32 spi_clk;
- u32 status;
- bool xfer_failed;
- bool use_dma;
- };
- static void dma_callback(void *data)
- {
- struct spi_controller *ctlr = data;
- struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
- at91_usart_spi_writel(aus, IER, US_IR_RXRDY);
- aus->current_rx_remaining_bytes = 0;
- complete(&aus->xfer_completion);
- }
- static bool at91_usart_spi_can_dma(struct spi_controller *ctrl,
- struct spi_device *spi,
- struct spi_transfer *xfer)
- {
- struct at91_usart_spi *aus = spi_master_get_devdata(ctrl);
- return aus->use_dma && xfer->len >= US_DMA_MIN_BYTES;
- }
- static int at91_usart_spi_configure_dma(struct spi_controller *ctlr,
- struct at91_usart_spi *aus)
- {
- struct dma_slave_config slave_config;
- struct device *dev = &aus->mpdev->dev;
- phys_addr_t phybase = aus->phybase;
- dma_cap_mask_t mask;
- int err = 0;
- dma_cap_zero(mask);
- dma_cap_set(DMA_SLAVE, mask);
- ctlr->dma_tx = dma_request_chan(dev, "tx");
- if (IS_ERR_OR_NULL(ctlr->dma_tx)) {
- if (IS_ERR(ctlr->dma_tx)) {
- err = PTR_ERR(ctlr->dma_tx);
- goto at91_usart_spi_error_clear;
- }
- dev_dbg(dev,
- "DMA TX channel not available, SPI unable to use DMA\n");
- err = -EBUSY;
- goto at91_usart_spi_error_clear;
- }
- ctlr->dma_rx = dma_request_chan(dev, "rx");
- if (IS_ERR_OR_NULL(ctlr->dma_rx)) {
- if (IS_ERR(ctlr->dma_rx)) {
- err = PTR_ERR(ctlr->dma_rx);
- goto at91_usart_spi_error;
- }
- dev_dbg(dev,
- "DMA RX channel not available, SPI unable to use DMA\n");
- err = -EBUSY;
- goto at91_usart_spi_error;
- }
- slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
- slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
- slave_config.dst_addr = (dma_addr_t)phybase + US_THR;
- slave_config.src_addr = (dma_addr_t)phybase + US_RHR;
- slave_config.src_maxburst = 1;
- slave_config.dst_maxburst = 1;
- slave_config.device_fc = false;
- slave_config.direction = DMA_DEV_TO_MEM;
- if (dmaengine_slave_config(ctlr->dma_rx, &slave_config)) {
- dev_err(&ctlr->dev,
- "failed to configure rx dma channel\n");
- err = -EINVAL;
- goto at91_usart_spi_error;
- }
- slave_config.direction = DMA_MEM_TO_DEV;
- if (dmaengine_slave_config(ctlr->dma_tx, &slave_config)) {
- dev_err(&ctlr->dev,
- "failed to configure tx dma channel\n");
- err = -EINVAL;
- goto at91_usart_spi_error;
- }
- aus->use_dma = true;
- return 0;
- at91_usart_spi_error:
- if (!IS_ERR_OR_NULL(ctlr->dma_tx))
- dma_release_channel(ctlr->dma_tx);
- if (!IS_ERR_OR_NULL(ctlr->dma_rx))
- dma_release_channel(ctlr->dma_rx);
- ctlr->dma_tx = NULL;
- ctlr->dma_rx = NULL;
- at91_usart_spi_error_clear:
- return err;
- }
- static void at91_usart_spi_release_dma(struct spi_controller *ctlr)
- {
- if (ctlr->dma_rx)
- dma_release_channel(ctlr->dma_rx);
- if (ctlr->dma_tx)
- dma_release_channel(ctlr->dma_tx);
- }
- static void at91_usart_spi_stop_dma(struct spi_controller *ctlr)
- {
- if (ctlr->dma_rx)
- dmaengine_terminate_all(ctlr->dma_rx);
- if (ctlr->dma_tx)
- dmaengine_terminate_all(ctlr->dma_tx);
- }
- static int at91_usart_spi_dma_transfer(struct spi_controller *ctlr,
- struct spi_transfer *xfer)
- {
- struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
- struct dma_chan *rxchan = ctlr->dma_rx;
- struct dma_chan *txchan = ctlr->dma_tx;
- struct dma_async_tx_descriptor *rxdesc;
- struct dma_async_tx_descriptor *txdesc;
- dma_cookie_t cookie;
- /* Disable RX interrupt */
- at91_usart_spi_writel(aus, IDR, US_IR_RXRDY);
- rxdesc = dmaengine_prep_slave_sg(rxchan,
- xfer->rx_sg.sgl,
- xfer->rx_sg.nents,
- DMA_DEV_TO_MEM,
- DMA_PREP_INTERRUPT |
- DMA_CTRL_ACK);
- if (!rxdesc)
- goto at91_usart_spi_err_dma;
- txdesc = dmaengine_prep_slave_sg(txchan,
- xfer->tx_sg.sgl,
- xfer->tx_sg.nents,
- DMA_MEM_TO_DEV,
- DMA_PREP_INTERRUPT |
- DMA_CTRL_ACK);
- if (!txdesc)
- goto at91_usart_spi_err_dma;
- rxdesc->callback = dma_callback;
- rxdesc->callback_param = ctlr;
- cookie = rxdesc->tx_submit(rxdesc);
- if (dma_submit_error(cookie))
- goto at91_usart_spi_err_dma;
- cookie = txdesc->tx_submit(txdesc);
- if (dma_submit_error(cookie))
- goto at91_usart_spi_err_dma;
- rxchan->device->device_issue_pending(rxchan);
- txchan->device->device_issue_pending(txchan);
- return 0;
- at91_usart_spi_err_dma:
- /* Enable RX interrupt if something fails and fallback to PIO */
- at91_usart_spi_writel(aus, IER, US_IR_RXRDY);
- at91_usart_spi_stop_dma(ctlr);
- return -ENOMEM;
- }
- static unsigned long at91_usart_spi_dma_timeout(struct at91_usart_spi *aus)
- {
- return wait_for_completion_timeout(&aus->xfer_completion,
- US_DMA_TIMEOUT);
- }
- static inline u32 at91_usart_spi_tx_ready(struct at91_usart_spi *aus)
- {
- return aus->status & US_IR_TXRDY;
- }
- static inline u32 at91_usart_spi_rx_ready(struct at91_usart_spi *aus)
- {
- return aus->status & US_IR_RXRDY;
- }
- static inline u32 at91_usart_spi_check_overrun(struct at91_usart_spi *aus)
- {
- return aus->status & US_IR_OVRE;
- }
- static inline u32 at91_usart_spi_read_status(struct at91_usart_spi *aus)
- {
- aus->status = at91_usart_spi_readl(aus, CSR);
- return aus->status;
- }
- static inline void at91_usart_spi_tx(struct at91_usart_spi *aus)
- {
- unsigned int len = aus->current_transfer->len;
- unsigned int remaining = aus->current_tx_remaining_bytes;
- const u8 *tx_buf = aus->current_transfer->tx_buf;
- if (!remaining)
- return;
- if (at91_usart_spi_tx_ready(aus)) {
- at91_usart_spi_writeb(aus, THR, tx_buf[len - remaining]);
- aus->current_tx_remaining_bytes--;
- }
- }
- static inline void at91_usart_spi_rx(struct at91_usart_spi *aus)
- {
- int len = aus->current_transfer->len;
- int remaining = aus->current_rx_remaining_bytes;
- u8 *rx_buf = aus->current_transfer->rx_buf;
- if (!remaining)
- return;
- rx_buf[len - remaining] = at91_usart_spi_readb(aus, RHR);
- aus->current_rx_remaining_bytes--;
- }
- static inline void
- at91_usart_spi_set_xfer_speed(struct at91_usart_spi *aus,
- struct spi_transfer *xfer)
- {
- at91_usart_spi_writel(aus, BRGR,
- DIV_ROUND_UP(aus->spi_clk, xfer->speed_hz));
- }
- static irqreturn_t at91_usart_spi_interrupt(int irq, void *dev_id)
- {
- struct spi_controller *controller = dev_id;
- struct at91_usart_spi *aus = spi_master_get_devdata(controller);
- spin_lock(&aus->lock);
- at91_usart_spi_read_status(aus);
- if (at91_usart_spi_check_overrun(aus)) {
- aus->xfer_failed = true;
- at91_usart_spi_writel(aus, IDR, US_IR_OVRE | US_IR_RXRDY);
- spin_unlock(&aus->lock);
- return IRQ_HANDLED;
- }
- if (at91_usart_spi_rx_ready(aus)) {
- at91_usart_spi_rx(aus);
- spin_unlock(&aus->lock);
- return IRQ_HANDLED;
- }
- spin_unlock(&aus->lock);
- return IRQ_NONE;
- }
- static int at91_usart_spi_setup(struct spi_device *spi)
- {
- struct at91_usart_spi *aus = spi_master_get_devdata(spi->controller);
- u32 *ausd = spi->controller_state;
- unsigned int mr = at91_usart_spi_readl(aus, MR);
- if (spi->mode & SPI_CPOL)
- mr |= US_MR_CPOL;
- else
- mr &= ~US_MR_CPOL;
- if (spi->mode & SPI_CPHA)
- mr |= US_MR_CPHA;
- else
- mr &= ~US_MR_CPHA;
- if (spi->mode & SPI_LOOP)
- mr |= US_MR_LOOP;
- else
- mr &= ~US_MR_LOOP;
- if (!ausd) {
- ausd = kzalloc(sizeof(*ausd), GFP_KERNEL);
- if (!ausd)
- return -ENOMEM;
- spi->controller_state = ausd;
- }
- *ausd = mr;
- dev_dbg(&spi->dev,
- "setup: bpw %u mode 0x%x -> mr %d %08x\n",
- spi->bits_per_word, spi->mode, spi->chip_select, mr);
- return 0;
- }
- static int at91_usart_spi_transfer_one(struct spi_controller *ctlr,
- struct spi_device *spi,
- struct spi_transfer *xfer)
- {
- struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
- unsigned long dma_timeout = 0;
- int ret = 0;
- at91_usart_spi_set_xfer_speed(aus, xfer);
- aus->xfer_failed = false;
- aus->current_transfer = xfer;
- aus->current_tx_remaining_bytes = xfer->len;
- aus->current_rx_remaining_bytes = xfer->len;
- while ((aus->current_tx_remaining_bytes ||
- aus->current_rx_remaining_bytes) && !aus->xfer_failed) {
- reinit_completion(&aus->xfer_completion);
- if (at91_usart_spi_can_dma(ctlr, spi, xfer) &&
- !ret) {
- ret = at91_usart_spi_dma_transfer(ctlr, xfer);
- if (ret)
- continue;
- dma_timeout = at91_usart_spi_dma_timeout(aus);
- if (WARN_ON(dma_timeout == 0)) {
- dev_err(&spi->dev, "DMA transfer timeout\n");
- return -EIO;
- }
- aus->current_tx_remaining_bytes = 0;
- } else {
- at91_usart_spi_read_status(aus);
- at91_usart_spi_tx(aus);
- }
- cpu_relax();
- }
- if (aus->xfer_failed) {
- dev_err(aus->dev, "Overrun!\n");
- return -EIO;
- }
- return 0;
- }
- static int at91_usart_spi_prepare_message(struct spi_controller *ctlr,
- struct spi_message *message)
- {
- struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
- struct spi_device *spi = message->spi;
- u32 *ausd = spi->controller_state;
- at91_usart_spi_writel(aus, CR, US_ENABLE);
- at91_usart_spi_writel(aus, IER, US_OVRE_RXRDY_IRQS);
- at91_usart_spi_writel(aus, MR, *ausd);
- return 0;
- }
- static int at91_usart_spi_unprepare_message(struct spi_controller *ctlr,
- struct spi_message *message)
- {
- struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
- at91_usart_spi_writel(aus, CR, US_RESET | US_DISABLE);
- at91_usart_spi_writel(aus, IDR, US_OVRE_RXRDY_IRQS);
- return 0;
- }
- static void at91_usart_spi_cleanup(struct spi_device *spi)
- {
- struct at91_usart_spi_device *ausd = spi->controller_state;
- spi->controller_state = NULL;
- kfree(ausd);
- }
- static void at91_usart_spi_init(struct at91_usart_spi *aus)
- {
- at91_usart_spi_writel(aus, MR, US_INIT);
- at91_usart_spi_writel(aus, CR, US_RESET | US_DISABLE);
- }
- static int at91_usart_gpio_setup(struct platform_device *pdev)
- {
- struct gpio_descs *cs_gpios;
- cs_gpios = devm_gpiod_get_array_optional(&pdev->dev, "cs", GPIOD_OUT_LOW);
- if (IS_ERR(cs_gpios))
- return PTR_ERR(cs_gpios);
- return 0;
- }
- static int at91_usart_spi_probe(struct platform_device *pdev)
- {
- struct resource *regs;
- struct spi_controller *controller;
- struct at91_usart_spi *aus;
- struct clk *clk;
- int irq;
- int ret;
- regs = platform_get_resource(to_platform_device(pdev->dev.parent),
- IORESOURCE_MEM, 0);
- if (!regs)
- return -EINVAL;
- irq = platform_get_irq(to_platform_device(pdev->dev.parent), 0);
- if (irq < 0)
- return irq;
- clk = devm_clk_get(pdev->dev.parent, "usart");
- if (IS_ERR(clk))
- return PTR_ERR(clk);
- ret = -ENOMEM;
- controller = spi_alloc_master(&pdev->dev, sizeof(*aus));
- if (!controller)
- goto at91_usart_spi_probe_fail;
- ret = at91_usart_gpio_setup(pdev);
- if (ret)
- goto at91_usart_spi_probe_fail;
- controller->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP | SPI_CS_HIGH;
- controller->dev.of_node = pdev->dev.parent->of_node;
- controller->bits_per_word_mask = SPI_BPW_MASK(8);
- controller->setup = at91_usart_spi_setup;
- controller->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX;
- controller->transfer_one = at91_usart_spi_transfer_one;
- controller->prepare_message = at91_usart_spi_prepare_message;
- controller->unprepare_message = at91_usart_spi_unprepare_message;
- controller->can_dma = at91_usart_spi_can_dma;
- controller->cleanup = at91_usart_spi_cleanup;
- controller->max_speed_hz = DIV_ROUND_UP(clk_get_rate(clk),
- US_MIN_CLK_DIV);
- controller->min_speed_hz = DIV_ROUND_UP(clk_get_rate(clk),
- US_MAX_CLK_DIV);
- platform_set_drvdata(pdev, controller);
- aus = spi_master_get_devdata(controller);
- aus->dev = &pdev->dev;
- aus->regs = devm_ioremap_resource(&pdev->dev, regs);
- if (IS_ERR(aus->regs)) {
- ret = PTR_ERR(aus->regs);
- goto at91_usart_spi_probe_fail;
- }
- aus->irq = irq;
- aus->clk = clk;
- ret = devm_request_irq(&pdev->dev, irq, at91_usart_spi_interrupt, 0,
- dev_name(&pdev->dev), controller);
- if (ret)
- goto at91_usart_spi_probe_fail;
- ret = clk_prepare_enable(clk);
- if (ret)
- goto at91_usart_spi_probe_fail;
- aus->spi_clk = clk_get_rate(clk);
- at91_usart_spi_init(aus);
- aus->phybase = regs->start;
- aus->mpdev = to_platform_device(pdev->dev.parent);
- ret = at91_usart_spi_configure_dma(controller, aus);
- if (ret)
- goto at91_usart_fail_dma;
- spin_lock_init(&aus->lock);
- init_completion(&aus->xfer_completion);
- ret = devm_spi_register_master(&pdev->dev, controller);
- if (ret)
- goto at91_usart_fail_register_master;
- dev_info(&pdev->dev,
- "AT91 USART SPI Controller version 0x%x at %pa (irq %d)\n",
- at91_usart_spi_readl(aus, VERSION),
- ®s->start, irq);
- return 0;
- at91_usart_fail_register_master:
- at91_usart_spi_release_dma(controller);
- at91_usart_fail_dma:
- clk_disable_unprepare(clk);
- at91_usart_spi_probe_fail:
- spi_master_put(controller);
- return ret;
- }
- __maybe_unused static int at91_usart_spi_runtime_suspend(struct device *dev)
- {
- struct spi_controller *ctlr = dev_get_drvdata(dev);
- struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
- clk_disable_unprepare(aus->clk);
- pinctrl_pm_select_sleep_state(dev);
- return 0;
- }
- __maybe_unused static int at91_usart_spi_runtime_resume(struct device *dev)
- {
- struct spi_controller *ctrl = dev_get_drvdata(dev);
- struct at91_usart_spi *aus = spi_master_get_devdata(ctrl);
- pinctrl_pm_select_default_state(dev);
- return clk_prepare_enable(aus->clk);
- }
- __maybe_unused static int at91_usart_spi_suspend(struct device *dev)
- {
- struct spi_controller *ctrl = dev_get_drvdata(dev);
- int ret;
- ret = spi_controller_suspend(ctrl);
- if (ret)
- return ret;
- if (!pm_runtime_suspended(dev))
- at91_usart_spi_runtime_suspend(dev);
- return 0;
- }
- __maybe_unused static int at91_usart_spi_resume(struct device *dev)
- {
- struct spi_controller *ctrl = dev_get_drvdata(dev);
- struct at91_usart_spi *aus = spi_master_get_devdata(ctrl);
- int ret;
- if (!pm_runtime_suspended(dev)) {
- ret = at91_usart_spi_runtime_resume(dev);
- if (ret)
- return ret;
- }
- at91_usart_spi_init(aus);
- return spi_controller_resume(ctrl);
- }
- static int at91_usart_spi_remove(struct platform_device *pdev)
- {
- struct spi_controller *ctlr = platform_get_drvdata(pdev);
- struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
- at91_usart_spi_release_dma(ctlr);
- clk_disable_unprepare(aus->clk);
- return 0;
- }
- static const struct dev_pm_ops at91_usart_spi_pm_ops = {
- SET_SYSTEM_SLEEP_PM_OPS(at91_usart_spi_suspend, at91_usart_spi_resume)
- SET_RUNTIME_PM_OPS(at91_usart_spi_runtime_suspend,
- at91_usart_spi_runtime_resume, NULL)
- };
- static struct platform_driver at91_usart_spi_driver = {
- .driver = {
- .name = "at91_usart_spi",
- .pm = &at91_usart_spi_pm_ops,
- },
- .probe = at91_usart_spi_probe,
- .remove = at91_usart_spi_remove,
- };
- module_platform_driver(at91_usart_spi_driver);
- MODULE_DESCRIPTION("Microchip AT91 USART SPI Controller driver");
- MODULE_AUTHOR("Radu Pirea <[email protected]>");
- MODULE_LICENSE("GPL v2");
- MODULE_ALIAS("platform:at91_usart_spi");
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