diff options
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/Kconfig | 8 | ||||
| -rw-r--r-- | drivers/spi/Makefile | 1 | ||||
| -rw-r--r-- | drivers/spi/spi-at91-usart.c | 432 |
3 files changed, 441 insertions, 0 deletions
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig index 671d078349cc..2e259d0f4136 100644 --- a/drivers/spi/Kconfig +++ b/drivers/spi/Kconfig @@ -83,6 +83,14 @@ config SPI_ATMEL This selects a driver for the Atmel SPI Controller, present on many AT91 ARM chips. +config SPI_AT91_USART + tristate "Atmel USART Controller SPI driver" + depends on (ARCH_AT91 || COMPILE_TEST) + depends on MFD_AT91_USART + help + This selects a driver for the AT91 USART Controller as SPI Master, + present on AT91 and SAMA5 SoC series. + config SPI_AU1550 tristate "Au1550/Au1200/Au1300 SPI Controller" depends on MIPS_ALCHEMY diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile index a90d55970036..ad094fca36aa 100644 --- a/drivers/spi/Makefile +++ b/drivers/spi/Makefile @@ -16,6 +16,7 @@ obj-$(CONFIG_SPI_LOOPBACK_TEST) += spi-loopback-test.o obj-$(CONFIG_SPI_ALTERA) += spi-altera.o obj-$(CONFIG_SPI_ARMADA_3700) += spi-armada-3700.o obj-$(CONFIG_SPI_ATMEL) += spi-atmel.o +obj-$(CONFIG_SPI_AT91_USART) += spi-at91-usart.o obj-$(CONFIG_SPI_ATH79) += spi-ath79.o obj-$(CONFIG_SPI_AU1550) += spi-au1550.o obj-$(CONFIG_SPI_AXI_SPI_ENGINE) += spi-axi-spi-engine.o diff --git a/drivers/spi/spi-at91-usart.c b/drivers/spi/spi-at91-usart.c new file mode 100644 index 000000000000..a924657642fa --- /dev/null +++ b/drivers/spi/spi-at91-usart.c @@ -0,0 +1,432 @@ +// SPDX-License-Identifier: GPL-2.0 +// +// Driver for AT91 USART Controllers as SPI +// +// Copyright (C) 2018 Microchip Technology Inc. +// +// Author: Radu Pirea <radu.pirea@microchip.com> + +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/interrupt.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of_gpio.h> +#include <linux/platform_device.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) + +/* 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 spi_transfer *current_transfer; + void __iomem *regs; + struct device *dev; + struct clk *clk; + + /*used in interrupt to protect data reading*/ + spinlock_t lock; + + int irq; + unsigned int current_tx_remaining_bytes; + unsigned int current_rx_remaining_bytes; + + u32 spi_clk; + u32 status; + + bool xfer_failed; +}; + +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); + u8 bits = spi->bits_per_word; + + if (bits != 8) { + dev_dbg(&spi->dev, "Only 8 bits per word are supported\n"); + return -EINVAL; + } + + 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", + bits, 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); + + 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) { + 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 device_node *np = pdev->dev.parent->of_node; + int i; + int ret; + int nb; + + if (!np) + return -EINVAL; + + nb = of_gpio_named_count(np, "cs-gpios"); + for (i = 0; i < nb; i++) { + int cs_gpio = of_get_named_gpio(np, "cs-gpios", i); + + if (cs_gpio < 0) + return cs_gpio; + + if (gpio_is_valid(cs_gpio)) { + ret = devm_gpio_request_one(&pdev->dev, cs_gpio, + GPIOF_DIR_OUT, + dev_name(&pdev->dev)); + if (ret) + return ret; + } + } + + 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->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); + + spin_lock_init(&aus->lock); + 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: + clk_disable_unprepare(clk); +at91_usart_spi_probe_fail: + spi_master_put(controller); + return ret; +} + +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); + + clk_disable_unprepare(aus->clk); + + return 0; +} + +static const struct of_device_id at91_usart_spi_dt_ids[] = { + { .compatible = "microchip,at91sam9g45-usart-spi"}, + { /* sentinel */} +}; + +MODULE_DEVICE_TABLE(of, at91_usart_spi_dt_ids); + +static struct platform_driver at91_usart_spi_driver = { + .driver = { + .name = "at91_usart_spi", + }, + .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 <radu.pirea@microchip.com>"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:at91_usart_spi"); |