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Release 4.14 drivers/spi/spi-meson-spicc.c

Directory: drivers/spi
/*
 * Driver for Amlogic Meson SPI communication controller (SPICC)
 *
 * Copyright (C) BayLibre, SAS
 * Author: Neil Armstrong <narmstrong@baylibre.com>
 *
 * SPDX-License-Identifier: GPL-2.0+
 */

#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/spi/spi.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/reset.h>
#include <linux/gpio.h>

/*
 * The Meson SPICC controller could support DMA based transfers, but is not
 * implemented by the vendor code, and while having the registers documentation
 * it has never worked on the GXL Hardware.
 * The PIO mode is the only mode implemented, and due to badly designed HW :
 * - all transfers are cutted in 16 words burst because the FIFO hangs on
 *   TX underflow, and there is no TX "Half-Empty" interrupt, so we go by
 *   FIFO max size chunk only
 * - CS management is dumb, and goes UP between every burst, so is really a
 *   "Data Valid" signal than a Chip Select, GPIO link should be used instead
 *   to have a CS go down over the full transfer
 */


#define SPICC_MAX_FREQ	30000000

#define SPICC_MAX_BURST	128

/* Register Map */

#define SPICC_RXDATA	0x00


#define SPICC_TXDATA	0x04


#define SPICC_CONREG	0x08

#define SPICC_ENABLE		BIT(0)

#define SPICC_MODE_MASTER	BIT(1)

#define SPICC_XCH		BIT(2)

#define SPICC_SMC		BIT(3)

#define SPICC_POL		BIT(4)

#define SPICC_PHA		BIT(5)

#define SPICC_SSCTL		BIT(6)

#define SPICC_SSPOL		BIT(7)

#define SPICC_DRCTL_MASK	GENMASK(9, 8)

#define SPICC_DRCTL_IGNORE	0

#define SPICC_DRCTL_FALLING	1

#define SPICC_DRCTL_LOWLEVEL	2

#define SPICC_CS_MASK		GENMASK(13, 12)

#define SPICC_DATARATE_MASK	GENMASK(18, 16)

#define SPICC_DATARATE_DIV4	0

#define SPICC_DATARATE_DIV8	1

#define SPICC_DATARATE_DIV16	2

#define SPICC_DATARATE_DIV32	3

#define SPICC_BITLENGTH_MASK	GENMASK(24, 19)

#define SPICC_BURSTLENGTH_MASK	GENMASK(31, 25)


#define SPICC_INTREG	0x0c

#define SPICC_TE_EN	BIT(0) 
/* TX FIFO Empty Interrupt */

#define SPICC_TH_EN	BIT(1) 
/* TX FIFO Half-Full Interrupt */

#define SPICC_TF_EN	BIT(2) 
/* TX FIFO Full Interrupt */

#define SPICC_RR_EN	BIT(3) 
/* RX FIFO Ready Interrupt */

#define SPICC_RH_EN	BIT(4) 
/* RX FIFO Half-Full Interrupt */

#define SPICC_RF_EN	BIT(5) 
/* RX FIFO Full Interrupt */

#define SPICC_RO_EN	BIT(6) 
/* RX FIFO Overflow Interrupt */

#define SPICC_TC_EN	BIT(7) 
/* Transfert Complete Interrupt */


#define SPICC_DMAREG	0x10

#define SPICC_DMA_ENABLE		BIT(0)

#define SPICC_TXFIFO_THRESHOLD_MASK	GENMASK(5, 1)

#define SPICC_RXFIFO_THRESHOLD_MASK	GENMASK(10, 6)

#define SPICC_READ_BURST_MASK		GENMASK(14, 11)

#define SPICC_WRITE_BURST_MASK		GENMASK(18, 15)

#define SPICC_DMA_URGENT		BIT(19)

#define SPICC_DMA_THREADID_MASK		GENMASK(25, 20)

#define SPICC_DMA_BURSTNUM_MASK		GENMASK(31, 26)


#define SPICC_STATREG	0x14

#define SPICC_TE	BIT(0) 
/* TX FIFO Empty Interrupt */

#define SPICC_TH	BIT(1) 
/* TX FIFO Half-Full Interrupt */

#define SPICC_TF	BIT(2) 
/* TX FIFO Full Interrupt */

#define SPICC_RR	BIT(3) 
/* RX FIFO Ready Interrupt */

#define SPICC_RH	BIT(4) 
/* RX FIFO Half-Full Interrupt */

#define SPICC_RF	BIT(5) 
/* RX FIFO Full Interrupt */

#define SPICC_RO	BIT(6) 
/* RX FIFO Overflow Interrupt */

#define SPICC_TC	BIT(7) 
/* Transfert Complete Interrupt */


#define SPICC_PERIODREG	0x18

#define SPICC_PERIOD	GENMASK(14, 0)	
/* Wait cycles */


#define SPICC_TESTREG	0x1c

#define SPICC_TXCNT_MASK	GENMASK(4, 0)	
/* TX FIFO Counter */

#define SPICC_RXCNT_MASK	GENMASK(9, 5)	
/* RX FIFO Counter */

#define SPICC_SMSTATUS_MASK	GENMASK(12, 10)	
/* State Machine Status */

#define SPICC_LBC_RO		BIT(13)	
/* Loop Back Control Read-Only */

#define SPICC_LBC_W1		BIT(14) 
/* Loop Back Control Write-Only */

#define SPICC_SWAP_RO		BIT(14) 
/* RX FIFO Data Swap Read-Only */

#define SPICC_SWAP_W1		BIT(15) 
/* RX FIFO Data Swap Write-Only */

#define SPICC_DLYCTL_RO_MASK	GENMASK(20, 15) 
/* Delay Control Read-Only */

#define SPICC_DLYCTL_W1_MASK	GENMASK(21, 16) 
/* Delay Control Write-Only */

#define SPICC_FIFORST_RO_MASK	GENMASK(22, 21) 
/* FIFO Softreset Read-Only */

#define SPICC_FIFORST_W1_MASK	GENMASK(23, 22) 
/* FIFO Softreset Write-Only */


#define SPICC_DRADDR	0x20	
/* Read Address of DMA */


#define SPICC_DWADDR	0x24	
/* Write Address of DMA */


#define writel_bits_relaxed(mask, val, addr) \
	writel_relaxed((readl_relaxed(addr) & ~(mask)) | (val), addr)


#define SPICC_BURST_MAX	16

#define SPICC_FIFO_HALF 10


struct meson_spicc_device {
	
struct spi_master		*master;
	
struct platform_device		*pdev;
	
void __iomem			*base;
	
struct clk			*core;
	
struct spi_message		*message;
	
struct spi_transfer		*xfer;
	
u8				*tx_buf;
	
u8				*rx_buf;
	
unsigned int			bytes_per_word;
	
unsigned long			tx_remain;
	
unsigned long			txb_remain;
	
unsigned long			rx_remain;
	
unsigned long			rxb_remain;
	
unsigned long			xfer_remain;
	
bool				is_burst_end;
	
bool				is_last_burst;
};


static inline bool meson_spicc_txfull(struct meson_spicc_device *spicc) { return !!FIELD_GET(SPICC_TF, readl_relaxed(spicc->base + SPICC_STATREG)); }

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static inline bool meson_spicc_rxready(struct meson_spicc_device *spicc) { return FIELD_GET(SPICC_RH | SPICC_RR | SPICC_RF_EN, readl_relaxed(spicc->base + SPICC_STATREG)); }

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static inline u32 meson_spicc_pull_data(struct meson_spicc_device *spicc) { unsigned int bytes = spicc->bytes_per_word; unsigned int byte_shift = 0; u32 data = 0; u8 byte; while (bytes--) { byte = *spicc->tx_buf++; data |= (byte & 0xff) << byte_shift; byte_shift += 8; } spicc->tx_remain--; return data; }

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static inline void meson_spicc_push_data(struct meson_spicc_device *spicc, u32 data) { unsigned int bytes = spicc->bytes_per_word; unsigned int byte_shift = 0; u8 byte; while (bytes--) { byte = (data >> byte_shift) & 0xff; *spicc->rx_buf++ = byte; byte_shift += 8; } spicc->rx_remain--; }

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static inline void meson_spicc_rx(struct meson_spicc_device *spicc) { /* Empty RX FIFO */ while (spicc->rx_remain && meson_spicc_rxready(spicc)) meson_spicc_push_data(spicc, readl_relaxed(spicc->base + SPICC_RXDATA)); }

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static inline void meson_spicc_tx(struct meson_spicc_device *spicc) { /* Fill Up TX FIFO */ while (spicc->tx_remain && !meson_spicc_txfull(spicc)) writel_relaxed(meson_spicc_pull_data(spicc), spicc->base + SPICC_TXDATA); }

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static inline u32 meson_spicc_setup_rx_irq(struct meson_spicc_device *spicc, u32 irq_ctrl) { if (spicc->rx_remain > SPICC_FIFO_HALF) irq_ctrl |= SPICC_RH_EN; else irq_ctrl |= SPICC_RR_EN; return irq_ctrl; }

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static inline void meson_spicc_setup_burst(struct meson_spicc_device *spicc, unsigned int burst_len) { /* Setup Xfer variables */ spicc->tx_remain = burst_len; spicc->rx_remain = burst_len; spicc->xfer_remain -= burst_len * spicc->bytes_per_word; spicc->is_burst_end = false; if (burst_len < SPICC_BURST_MAX || !spicc->xfer_remain) spicc->is_last_burst = true; else spicc->is_last_burst = false; /* Setup burst length */ writel_bits_relaxed(SPICC_BURSTLENGTH_MASK, FIELD_PREP(SPICC_BURSTLENGTH_MASK, burst_len), spicc->base + SPICC_CONREG); /* Fill TX FIFO */ meson_spicc_tx(spicc); }

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static irqreturn_t meson_spicc_irq(int irq, void *data) { struct meson_spicc_device *spicc = (void *) data; u32 ctrl = readl_relaxed(spicc->base + SPICC_INTREG); u32 stat = readl_relaxed(spicc->base + SPICC_STATREG) & ctrl; ctrl &= ~(SPICC_RH_EN | SPICC_RR_EN); /* Empty RX FIFO */ meson_spicc_rx(spicc); /* Enable TC interrupt since we transferred everything */ if (!spicc->tx_remain && !spicc->rx_remain) { spicc->is_burst_end = true; /* Enable TC interrupt */ ctrl |= SPICC_TC_EN; /* Reload IRQ status */ stat = readl_relaxed(spicc->base + SPICC_STATREG) & ctrl; } /* Check transfer complete */ if ((stat & SPICC_TC) && spicc->is_burst_end) { unsigned int burst_len; /* Clear TC bit */ writel_relaxed(SPICC_TC, spicc->base + SPICC_STATREG); /* Disable TC interrupt */ ctrl &= ~SPICC_TC_EN; if (spicc->is_last_burst) { /* Disable all IRQs */ writel(0, spicc->base + SPICC_INTREG); spi_finalize_current_transfer(spicc->master); return IRQ_HANDLED; } burst_len = min_t(unsigned int, spicc->xfer_remain / spicc->bytes_per_word, SPICC_BURST_MAX); /* Setup burst */ meson_spicc_setup_burst(spicc, burst_len); /* Restart burst */ writel_bits_relaxed(SPICC_XCH, SPICC_XCH, spicc->base + SPICC_CONREG); } /* Setup RX interrupt trigger */ ctrl = meson_spicc_setup_rx_irq(spicc, ctrl); /* Reconfigure interrupts */ writel(ctrl, spicc->base + SPICC_INTREG); return IRQ_HANDLED; }

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static u32 meson_spicc_setup_speed(struct meson_spicc_device *spicc, u32 conf, u32 speed) { unsigned long parent, value; unsigned int i, div; parent = clk_get_rate(spicc->core); /* Find closest inferior/equal possible speed */ for (i = 0 ; i < 7 ; ++i) { /* 2^(data_rate+2) */ value = parent >> (i + 2); if (value <= speed) break; } /* If provided speed it lower than max divider, use max divider */ if (i > 7) { div = 7; dev_warn_once(&spicc->pdev->dev, "unable to get close to speed %u\n", speed); } else div = i; dev_dbg(&spicc->pdev->dev, "parent %lu, speed %u -> %lu (%u)\n", parent, speed, value, div); conf &= ~SPICC_DATARATE_MASK; conf |= FIELD_PREP(SPICC_DATARATE_MASK, div); return conf; }

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static void meson_spicc_setup_xfer(struct meson_spicc_device *spicc, struct spi_transfer *xfer) { u32 conf, conf_orig; /* Read original configuration */ conf = conf_orig = readl_relaxed(spicc->base + SPICC_CONREG); /* Select closest divider */ conf = meson_spicc_setup_speed(spicc, conf, xfer->speed_hz); /* Setup word width */ conf &= ~SPICC_BITLENGTH_MASK; conf |= FIELD_PREP(SPICC_BITLENGTH_MASK, (spicc->bytes_per_word << 3) - 1); /* Ignore if unchanged */ if (conf != conf_orig) writel_relaxed(conf, spicc->base + SPICC_CONREG); }

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static int meson_spicc_transfer_one(struct spi_master *master, struct spi_device *spi, struct spi_transfer *xfer) { struct meson_spicc_device *spicc = spi_master_get_devdata(master); unsigned int burst_len; u32 irq = 0; /* Store current transfer */ spicc->xfer = xfer; /* Setup transfer parameters */ spicc->tx_buf = (u8 *)xfer->tx_buf; spicc->rx_buf = (u8 *)xfer->rx_buf; spicc->xfer_remain = xfer->len; /* Pre-calculate word size */ spicc->bytes_per_word = DIV_ROUND_UP(spicc->xfer->bits_per_word, 8); /* Setup transfer parameters */ meson_spicc_setup_xfer(spicc, xfer); burst_len = min_t(unsigned int, spicc->xfer_remain / spicc->bytes_per_word, SPICC_BURST_MAX); meson_spicc_setup_burst(spicc, burst_len); irq = meson_spicc_setup_rx_irq(spicc, irq); /* Start burst */ writel_bits_relaxed(SPICC_XCH, SPICC_XCH, spicc->base + SPICC_CONREG); /* Enable interrupts */ writel_relaxed(irq, spicc->base + SPICC_INTREG); return 1; }

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static int meson_spicc_prepare_message(struct spi_master *master, struct spi_message *message) { struct meson_spicc_device *spicc = spi_master_get_devdata(master); struct spi_device *spi = message->spi; u32 conf = 0; /* Store current message */ spicc->message = message; /* Enable Master */ conf |= SPICC_ENABLE; conf |= SPICC_MODE_MASTER; /* SMC = 0 */ /* Setup transfer mode */ if (spi->mode & SPI_CPOL) conf |= SPICC_POL; else conf &= ~SPICC_POL; if (spi->mode & SPI_CPHA) conf |= SPICC_PHA; else conf &= ~SPICC_PHA; /* SSCTL = 0 */ if (spi->mode & SPI_CS_HIGH) conf |= SPICC_SSPOL; else conf &= ~SPICC_SSPOL; if (spi->mode & SPI_READY) conf |= FIELD_PREP(SPICC_DRCTL_MASK, SPICC_DRCTL_LOWLEVEL); else conf |= FIELD_PREP(SPICC_DRCTL_MASK, SPICC_DRCTL_IGNORE); /* Select CS */ conf |= FIELD_PREP(SPICC_CS_MASK, spi->chip_select); /* Default Clock rate core/4 */ /* Default 8bit word */ conf |= FIELD_PREP(SPICC_BITLENGTH_MASK, 8 - 1); writel_relaxed(conf, spicc->base + SPICC_CONREG); /* Setup no wait cycles by default */ writel_relaxed(0, spicc->base + SPICC_PERIODREG); writel_bits_relaxed(BIT(24), BIT(24), spicc->base + SPICC_TESTREG); return 0; }

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static int meson_spicc_unprepare_transfer(struct spi_master *master) { struct meson_spicc_device *spicc = spi_master_get_devdata(master); /* Disable all IRQs */ writel(0, spicc->base + SPICC_INTREG); /* Disable controller */ writel_bits_relaxed(SPICC_ENABLE, 0, spicc->base + SPICC_CONREG); device_reset_optional(&spicc->pdev->dev); return 0; }

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static int meson_spicc_setup(struct spi_device *spi) { int ret = 0; if (!spi->controller_state) spi->controller_state = spi_master_get_devdata(spi->master); else if (gpio_is_valid(spi->cs_gpio)) goto out_gpio; else if (spi->cs_gpio == -ENOENT) return 0; if (gpio_is_valid(spi->cs_gpio)) { ret = gpio_request(spi->cs_gpio, dev_name(&spi->dev)); if (ret) { dev_err(&spi->dev, "failed to request cs gpio\n"); return ret; } } out_gpio: ret = gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH)); return ret; }

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static void meson_spicc_cleanup(struct spi_device *spi) { if (gpio_is_valid(spi->cs_gpio)) gpio_free(spi->cs_gpio); spi->controller_state = NULL; }

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static int meson_spicc_probe(struct platform_device *pdev) { struct spi_master *master; struct meson_spicc_device *spicc; struct resource *res; int ret, irq, rate; master = spi_alloc_master(&pdev->dev, sizeof(*spicc)); if (!master) { dev_err(&pdev->dev, "master allocation failed\n"); return -ENOMEM; } spicc = spi_master_get_devdata(master); spicc->master = master; spicc->pdev = pdev; platform_set_drvdata(pdev, spicc); res = platform_get_resource(pdev, IORESOURCE_MEM, 0); spicc->base = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(spicc->base)) { dev_err(&pdev->dev, "io resource mapping failed\n"); ret = PTR_ERR(spicc->base); goto out_master; } /* Disable all IRQs */ writel_relaxed(0, spicc->base + SPICC_INTREG); irq = platform_get_irq(pdev, 0); ret = devm_request_irq(&pdev->dev, irq, meson_spicc_irq, 0, NULL, spicc); if (ret) { dev_err(&pdev->dev, "irq request failed\n"); goto out_master; } spicc->core = devm_clk_get(&pdev->dev, "core"); if (IS_ERR(spicc->core)) { dev_err(&pdev->dev, "core clock request failed\n"); ret = PTR_ERR(spicc->core); goto out_master; } ret = clk_prepare_enable(spicc->core); if (ret) { dev_err(&pdev->dev, "core clock enable failed\n"); goto out_master; } rate = clk_get_rate(spicc->core); device_reset_optional(&pdev->dev); master->num_chipselect = 4; master->dev.of_node = pdev->dev.of_node; master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_CS_HIGH; master->bits_per_word_mask = SPI_BPW_MASK(32) | SPI_BPW_MASK(24) | SPI_BPW_MASK(16) | SPI_BPW_MASK(8); master->flags = (SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX); master->min_speed_hz = rate >> 9; master->setup = meson_spicc_setup; master->cleanup = meson_spicc_cleanup; master->prepare_message = meson_spicc_prepare_message; master->unprepare_transfer_hardware = meson_spicc_unprepare_transfer; master->transfer_one = meson_spicc_transfer_one; /* Setup max rate according to the Meson GX datasheet */ if ((rate >> 2) > SPICC_MAX_FREQ) master->max_speed_hz = SPICC_MAX_FREQ; else master->max_speed_hz = rate >> 2; ret = devm_spi_register_master(&pdev->dev, master); if (!ret) return 0; dev_err(&pdev->dev, "spi master registration failed\n"); out_master: spi_master_put(master); return ret; }

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static int meson_spicc_remove(struct platform_device *pdev) { struct meson_spicc_device *spicc = platform_get_drvdata(pdev); /* Disable SPI */ writel(0, spicc->base + SPICC_CONREG); clk_disable_unprepare(spicc->core); return 0; }

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static const struct of_device_id meson_spicc_of_match[] = { { .compatible = "amlogic,meson-gx-spicc", }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, meson_spicc_of_match); static struct platform_driver meson_spicc_driver = { .probe = meson_spicc_probe, .remove = meson_spicc_remove, .driver = { .name = "meson-spicc", .of_match_table = of_match_ptr(meson_spicc_of_match), }, }; module_platform_driver(meson_spicc_driver); MODULE_DESCRIPTION("Meson SPI Communication Controller driver"); MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>"); MODULE_LICENSE("GPL");

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Directory: drivers/spi
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