From: Thor Thayer <thor.thayer@xxxxxxxxxxxxxxx> Add driver support for the Altera I2C Controller. The I2C controller is soft IP for use in FPGAs. Signed-off-by: Thor Thayer <thor.thayer@xxxxxxxxxxxxxxx> --- drivers/i2c/busses/Kconfig | 10 + drivers/i2c/busses/Makefile | 1 + drivers/i2c/busses/i2c-altera.c | 509 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 520 insertions(+) create mode 100644 drivers/i2c/busses/i2c-altera.c diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig index 144cbad..981ea48 100644 --- a/drivers/i2c/busses/Kconfig +++ b/drivers/i2c/busses/Kconfig @@ -326,6 +326,16 @@ config I2C_POWERMAC comment "I2C system bus drivers (mostly embedded / system-on-chip)" +config I2C_ALTERA + tristate "Altera Soft IP I2C" + depends on (ARCH_SOCFPGA || NIOS2) && OF + help + If you say yes to this option, support will be included for the + Altera Soft IP I2C interfaces on SoCFPGA and Nios2 architectures. + + This driver can also be built as a module. If so, the module + will be called i2c-altera. + config I2C_AT91 tristate "Atmel AT91 I2C Two-Wire interface (TWI)" depends on ARCH_AT91 diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile index 30b6085..4eb5c82 100644 --- a/drivers/i2c/busses/Makefile +++ b/drivers/i2c/busses/Makefile @@ -29,6 +29,7 @@ obj-$(CONFIG_I2C_HYDRA) += i2c-hydra.o obj-$(CONFIG_I2C_POWERMAC) += i2c-powermac.o # Embedded system I2C/SMBus host controller drivers +obj-$(CONFIG_I2C_ALTERA) += i2c-altera.o obj-$(CONFIG_I2C_AT91) += i2c-at91.o obj-$(CONFIG_I2C_AU1550) += i2c-au1550.o obj-$(CONFIG_I2C_AXXIA) += i2c-axxia.o diff --git a/drivers/i2c/busses/i2c-altera.c b/drivers/i2c/busses/i2c-altera.c new file mode 100644 index 0000000..cd2d732 --- /dev/null +++ b/drivers/i2c/busses/i2c-altera.c @@ -0,0 +1,509 @@ +/* + * Copyright Intel Corporation (C) 2017. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program. If not, see <http://www.gnu.org/licenses/>. + * + * Based on the i2c-axxia.c driver. + */ +#include <linux/clk.h> +#include <linux/clkdev.h> +#include <linux/err.h> +#include <linux/i2c.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/platform_device.h> + +#define ALTR_I2C_TFR_CMD 0x00 /* Transfer Command register */ +#define ALTR_I2C_TFR_CMD_STA BIT(9) /* send START before byte */ +#define ALTR_I2C_TFR_CMD_STO BIT(8) /* send STOP after byte */ +#define ALTR_I2C_TFR_CMD_RW_D BIT(0) /* Direction of transfer */ +#define ALTR_I2C_RX_DATA 0x04 /* RX data FIFO register */ +#define ALTR_I2C_CTRL 0x08 /* Control register */ +#define ALTR_I2C_CTRL_RXT_SHFT 4 /* RX FIFO Threshold */ +#define ALTR_I2C_CTRL_TCT_SHFT 2 /* TFER CMD FIFO Threshold */ +#define ALTR_I2C_CTRL_BSPEED BIT(1) /* Bus Speed (1=Fast) */ +#define ALTR_I2C_CTRL_EN BIT(0) /* Enable Core (1=Enable) */ +#define ALTR_I2C_ISER 0x0C /* Interrupt Status Enable register */ +#define ALTR_I2C_ISER_RXOF_EN BIT(4) /* Enable RX OVERFLOW IRQ */ +#define ALTR_I2C_ISER_ARB_EN BIT(3) /* Enable ARB LOST IRQ */ +#define ALTR_I2C_ISER_NACK_EN BIT(2) /* Enable NACK DET IRQ */ +#define ALTR_I2C_ISER_RXRDY_EN BIT(1) /* Enable RX Ready IRQ */ +#define ALTR_I2C_ISER_TXRDY_EN BIT(0) /* Enable TX Ready IRQ */ +#define ALTR_I2C_ISR 0x10 /* Interrupt Status register */ +#define ALTR_I2C_ISR_RXOF BIT(4) /* RX OVERFLOW IRQ */ +#define ALTR_I2C_ISR_ARB BIT(3) /* ARB LOST IRQ */ +#define ALTR_I2C_ISR_NACK BIT(2) /* NACK DET IRQ */ +#define ALTR_I2C_ISR_RXRDY BIT(1) /* RX Ready IRQ */ +#define ALTR_I2C_ISR_TXRDY BIT(0) /* TX Ready IRQ */ +#define ALTR_I2C_STATUS 0x14 /* Status register */ +#define ALTR_I2C_STAT_CORE BIT(0) /* Core Status (0=idle) */ +#define ALTR_I2C_TC_FIFO_LVL 0x18 /* Transfer FIFO LVL register */ +#define ALTR_I2C_RX_FIFO_LVL 0x1C /* Receive FIFO LVL register */ +#define ALTR_I2C_SCL_LOW 0x20 /* SCL low count register */ +#define ALTR_I2C_SCL_HIGH 0x24 /* SCL high count register */ +#define ALTR_I2C_SDA_HOLD 0x28 /* SDA hold count register */ + +#define ALTR_I2C_ALL_IRQ (ALTR_I2C_ISR_RXOF | ALTR_I2C_ISR_ARB | \ + ALTR_I2C_ISR_NACK | ALTR_I2C_ISR_RXRDY | \ + ALTR_I2C_ISR_TXRDY) + +#define ALTR_I2C_THRESHOLD 0 /*IRQ Threshold at 1 element */ +#define ALTR_I2C_DFLT_FIFO_SZ 4 +#define ALTR_I2C_TIMEOUT 100 +#define ALTR_I2C_XFER_TIMEOUT (msecs_to_jiffies(250)) + +/** + * altr_i2c_dev - I2C device context + * @base: pointer to register struct + * @msg: pointer to current message + * @msg_len: number of bytes transferred in msg + * @msg_err: error code for completed message + * @msg_complete: xfer completion object + * @dev: device reference + * @adapter: core i2c abstraction + * @i2c_clk: clock reference for i2c input clock + * @bus_clk_rate: current i2c bus clock rate + * @buf: ptr to msg buffer for easier use. + * @fifo_size: size of the FIFO passed in. + */ +struct altr_i2c_dev { + void __iomem *base; + struct i2c_msg *msg; + size_t msg_len; + int msg_err; + struct completion msg_complete; + struct device *dev; + struct i2c_adapter adapter; + struct clk *i2c_clk; + u32 bus_clk_rate; + u8 *buf; + unsigned int fifo_size; +}; + +static void i2c_int_disable(struct altr_i2c_dev *idev, u32 mask) +{ + u32 int_en = readl(idev->base + ALTR_I2C_ISER); + + writel(int_en & ~mask, idev->base + ALTR_I2C_ISER); +} + +static void i2c_int_enable(struct altr_i2c_dev *idev, u32 mask) +{ + u32 int_en = readl(idev->base + ALTR_I2C_ISER); + + writel(int_en | mask, idev->base + ALTR_I2C_ISER); +} + +static void i2c_int_clear(struct altr_i2c_dev *idev, u32 mask) +{ + u32 int_en = readl(idev->base + ALTR_I2C_ISR); + + writel(int_en | mask, idev->base + ALTR_I2C_ISR); +} + +static void altr_i2c_core_disable(struct altr_i2c_dev *idev) +{ + u32 tmp = readl(idev->base + ALTR_I2C_CTRL); + + writel(tmp & ~ALTR_I2C_CTRL_EN, idev->base + ALTR_I2C_CTRL); +} + +static void altr_i2c_core_enable(struct altr_i2c_dev *idev) +{ + u32 tmp = readl(idev->base + ALTR_I2C_CTRL); + + writel(tmp | ALTR_I2C_CTRL_EN, idev->base + ALTR_I2C_CTRL); +} + +static void altr_i2c_reset(struct altr_i2c_dev *idev) +{ + altr_i2c_core_disable(idev); + altr_i2c_core_enable(idev); +} + +static void altr_i2c_recover(struct altr_i2c_dev *idev) +{ + altr_i2c_reset(idev); + /* Clock start bit + 8 bits + stop bit out */ + writel(ALTR_I2C_TFR_CMD_STA | ALTR_I2C_TFR_CMD_STO, + idev->base + ALTR_I2C_TFR_CMD); + altr_i2c_reset(idev); + + i2c_recover_bus(&idev->adapter); +} + +static inline void altr_i2c_stop(struct altr_i2c_dev *idev) +{ + writel(ALTR_I2C_TFR_CMD_STO, idev->base + ALTR_I2C_TFR_CMD); +} + +static void altr_i2c_init(struct altr_i2c_dev *idev) +{ + u32 divisor = clk_get_rate(idev->i2c_clk) / idev->bus_clk_rate; + u32 clk_mhz = clk_get_rate(idev->i2c_clk) / 1000000; + u32 tmp = (ALTR_I2C_THRESHOLD << ALTR_I2C_CTRL_RXT_SHFT) | + (ALTR_I2C_THRESHOLD << ALTR_I2C_CTRL_TCT_SHFT); + u32 t_high, t_low; + + if (idev->bus_clk_rate <= 100000) { + tmp &= ~ALTR_I2C_CTRL_BSPEED; + /* Standard mode SCL 50/50 */ + t_high = divisor * 1 / 2; + t_low = divisor * 1 / 2; + } else { + tmp |= ALTR_I2C_CTRL_BSPEED; + /* Fast mode SCL 33/66 */ + t_high = divisor * 1 / 3; + t_low = divisor * 2 / 3; + } + writel(tmp, idev->base + ALTR_I2C_CTRL); + + dev_dbg(idev->dev, "rate=%uHz per_clk=%uMHz -> ratio=1:%u\n", + idev->bus_clk_rate, clk_mhz, divisor); + + /* Reset controller */ + altr_i2c_reset(idev); + + /* SCL High Time */ + writel(t_high, idev->base + ALTR_I2C_SCL_HIGH); + /* SCL Low Time */ + writel(t_low, idev->base + ALTR_I2C_SCL_LOW); + /* SDA Hold Time, 300ns */ + writel(div_u64(300 * clk_mhz, 1000), idev->base + ALTR_I2C_SDA_HOLD); + + /* Mask all master interrupt bits */ + i2c_int_disable(idev, ~0); +} + +static int i2c_m_rd(const struct i2c_msg *msg) +{ + return (msg->flags & I2C_M_RD) != 0; +} + +/** + * altr_i2c_empty_rx_fifo - Fetch data from RX FIFO until end of + * transfer. Send a Stop bit on the last byte. + */ +static void altr_i2c_empty_rx_fifo(struct altr_i2c_dev *idev) +{ + size_t rx_fifo_avail = readl(idev->base + ALTR_I2C_RX_FIFO_LVL); + int bytes_to_transfer = min(rx_fifo_avail, idev->msg_len); + + while (bytes_to_transfer-- > 0) { + *idev->buf++ = readl(idev->base + ALTR_I2C_RX_DATA); + if (idev->msg_len == 1) + altr_i2c_stop(idev); + else + writel(0, idev->base + ALTR_I2C_TFR_CMD); + + idev->msg_len--; + } +} + +/** + * altr_i2c_fill_tx_fifo - Fill TX FIFO from current message buffer. + * @return: Number of bytes left to transfer. + */ +static int altr_i2c_fill_tx_fifo(struct altr_i2c_dev *idev) +{ + size_t tx_fifo_avail = idev->fifo_size - readl(idev->base + + ALTR_I2C_TC_FIFO_LVL); + int bytes_to_transfer = min(tx_fifo_avail, idev->msg_len); + int ret = idev->msg_len - bytes_to_transfer; + + while (bytes_to_transfer-- > 0) { + if (idev->msg_len == 1) + writel(ALTR_I2C_TFR_CMD_STO | *idev->buf++, + idev->base + ALTR_I2C_TFR_CMD); + else + writel(*idev->buf++, idev->base + ALTR_I2C_TFR_CMD); + idev->msg_len--; + } + + return ret; +} + +/** + * altr_i2c_wait_for_core_idle - After TX, check core idle for all bytes TX. + * @return: 0 on success or -ETIMEDOUT on timeout. + */ +static int altr_i2c_wait_for_core_idle(struct altr_i2c_dev *idev) +{ + unsigned long timeout = jiffies + msecs_to_jiffies(ALTR_I2C_TIMEOUT); + + do { + if (time_after(jiffies, timeout)) { + dev_err(idev->dev, "Core Idle timeout\n"); + return -ETIMEDOUT; + } + } while (readl(idev->base + ALTR_I2C_STATUS) & ALTR_I2C_STAT_CORE); + + return 0; +} + +static irqreturn_t altr_i2c_isr(int irq, void *_dev) +{ + struct altr_i2c_dev *idev = _dev; + /* Read IRQ status but only interested in Enabled IRQs. */ + u32 status = readl(idev->base + ALTR_I2C_ISR) & + readl(idev->base + ALTR_I2C_ISER); + + if (!idev->msg) { + dev_warn(idev->dev, "unexpected interrupt\n"); + goto out; + } + + /* handle Lost Arbitration */ + if (unlikely(status & ALTR_I2C_ISR_ARB)) { + dev_err(idev->dev, "%s: arbitration lost\n", __func__); + i2c_int_clear(idev, ALTR_I2C_ISR_ARB); + idev->msg_err = -EAGAIN; + goto complete; + } + + if (unlikely(status & ALTR_I2C_ISR_NACK)) { + dev_dbg(idev->dev, "%s: could not get ACK\n", __func__); + idev->msg_err = -ENXIO; + i2c_int_clear(idev, ALTR_I2C_ISR_NACK); + altr_i2c_stop(idev); + goto complete; + } + + /* handle RX FIFO Overflow */ + if (i2c_m_rd(idev->msg) && unlikely(status & ALTR_I2C_ISR_RXOF)) { + altr_i2c_empty_rx_fifo(idev); + i2c_int_clear(idev, ALTR_I2C_ISR_RXRDY); + altr_i2c_stop(idev); + dev_err(idev->dev, "%s: RX FIFO Overflow\n", __func__); + goto complete; + } + + /* RX FIFO needs service? */ + if (i2c_m_rd(idev->msg) && (status & ALTR_I2C_ISR_RXRDY)) { + altr_i2c_empty_rx_fifo(idev); + i2c_int_clear(idev, ALTR_I2C_ISR_RXRDY); + if (!idev->msg_len) + goto complete; + + goto out; + } + + /* TX FIFO needs service? */ + if (!i2c_m_rd(idev->msg) && (status & ALTR_I2C_ISR_TXRDY)) { + i2c_int_clear(idev, ALTR_I2C_ISR_TXRDY); + if (!altr_i2c_fill_tx_fifo(idev)) + goto complete; + + goto out; + } + +complete: + dev_dbg(idev->dev, "%s: Message Complete\n", __func__); + if (altr_i2c_wait_for_core_idle(idev)) + dev_err(idev->dev, "%s: message timeout\n", __func__); + i2c_int_disable(idev, ALTR_I2C_ALL_IRQ); + i2c_int_clear(idev, ALTR_I2C_ALL_IRQ); + complete(&idev->msg_complete); + +out: + return IRQ_HANDLED; +} + +static int altr_i2c_xfer_msg(struct altr_i2c_dev *idev, struct i2c_msg *msg) +{ + u32 int_mask = ALTR_I2C_ISR_RXOF | ALTR_I2C_ISR_ARB | ALTR_I2C_ISR_NACK; + u32 addr = (msg->addr << 1) & 0xFF; + unsigned long time_left; + + idev->msg = msg; + idev->msg_len = msg->len; + idev->buf = msg->buf; + idev->msg_err = 0; + reinit_completion(&idev->msg_complete); + altr_i2c_core_enable(idev); + + if (i2c_m_rd(msg)) { + /* Dummy read to ensure RX FIFO is empty */ + readl(idev->base + ALTR_I2C_RX_DATA); + addr |= ALTR_I2C_TFR_CMD_RW_D; + } + + writel(ALTR_I2C_TFR_CMD_STA | addr, idev->base + ALTR_I2C_TFR_CMD); + + if (i2c_m_rd(msg)) { + /* write the first byte to start the RX */ + writel(0, idev->base + ALTR_I2C_TFR_CMD); + int_mask |= ALTR_I2C_ISER_RXOF_EN | ALTR_I2C_ISER_RXRDY_EN; + } else { + altr_i2c_fill_tx_fifo(idev); + int_mask |= ALTR_I2C_ISR_TXRDY; + } + i2c_int_enable(idev, int_mask); + + time_left = wait_for_completion_timeout(&idev->msg_complete, + I2C_XFER_TIMEOUT); + + i2c_int_disable(idev, int_mask); + + if (readl(idev->base + ALTR_I2C_STATUS) & ALTR_I2C_STAT_CORE) + dev_err(idev->dev, "%s: Core Status not IDLE...\n", __func__); + + if (time_left == 0) { + idev->msg_err = -ETIMEDOUT; + dev_err(idev->dev, "%s: Transaction timed out.\n", __func__); + altr_i2c_recover(idev); + } + + if (unlikely(idev->msg_err) && idev->msg_err != -ENXIO) + altr_i2c_init(idev); + + altr_i2c_core_disable(idev); + + return idev->msg_err; +} + +static int +altr_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) +{ + struct altr_i2c_dev *idev = i2c_get_adapdata(adap); + int i; + int ret = 0; + + for (i = 0; ret == 0 && i < num; ++i) + ret = altr_i2c_xfer_msg(idev, &msgs[i]); + + return ret ? : i; +} + +static u32 altr_i2c_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C; +} + +static const struct i2c_algorithm altr_i2c_algo = { + .master_xfer = altr_i2c_xfer, + .functionality = altr_i2c_func, +}; + +static int altr_i2c_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct altr_i2c_dev *idev = NULL; + struct resource *res; + int irq; + int ret = 0; + + idev = devm_kzalloc(&pdev->dev, sizeof(*idev), GFP_KERNEL); + if (!idev) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + idev->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(idev->base)) + return PTR_ERR(idev->base); + + irq = platform_get_irq(pdev, 0); + if (irq < 0) { + dev_err(&pdev->dev, "missing interrupt resource\n"); + return irq; + } + + idev->i2c_clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(idev->i2c_clk)) { + dev_err(&pdev->dev, "missing clock\n"); + return PTR_ERR(idev->i2c_clk); + } + + idev->dev = &pdev->dev; + init_completion(&idev->msg_complete); + + if (of_property_read_u32(np, "altr,fifo-size", &idev->fifo_size)) + idev->fifo_size = ALTR_I2C_DFLT_FIFO_SZ; + + if (of_property_read_u32(np, "clock-frequency", &idev->bus_clk_rate)) + idev->bus_clk_rate = 100000; /* default clock rate */ + + if (idev->bus_clk_rate > 400000) { + dev_err(&pdev->dev, "invalid clock-frequency %d\n", + idev->bus_clk_rate); + return -EINVAL; + } + + ret = devm_request_irq(&pdev->dev, irq, altr_i2c_isr, 0, + pdev->name, idev); + if (ret) { + dev_err(&pdev->dev, "failed to claim IRQ%d\n", irq); + return ret; + } + + ret = clk_prepare_enable(idev->i2c_clk); + if (ret) { + dev_err(&pdev->dev, "failed to enable clock\n"); + return ret; + } + + altr_i2c_init(idev); + + i2c_set_adapdata(&idev->adapter, idev); + strlcpy(idev->adapter.name, pdev->name, sizeof(idev->adapter.name)); + idev->adapter.owner = THIS_MODULE; + idev->adapter.algo = &altr_i2c_algo; + idev->adapter.dev.parent = &pdev->dev; + idev->adapter.dev.of_node = pdev->dev.of_node; + + platform_set_drvdata(pdev, idev); + + ret = i2c_add_adapter(&idev->adapter); + if (ret) { + clk_disable_unprepare(idev->i2c_clk); + return ret; + } + dev_info(&pdev->dev, "Altera SoftIP I2C Probe Complete\n"); + + return 0; +} + +static int altr_i2c_remove(struct platform_device *pdev) +{ + struct altr_i2c_dev *idev = platform_get_drvdata(pdev); + + clk_disable_unprepare(idev->i2c_clk); + i2c_del_adapter(&idev->adapter); + + return 0; +} + +/* Match table for of_platform binding */ +static const struct of_device_id altr_i2c_of_match[] = { + { .compatible = "altr,sip-i2c" }, + {}, +}; +MODULE_DEVICE_TABLE(of, altr_i2c_of_match); + +static struct platform_driver altr_i2c_driver = { + .probe = altr_i2c_probe, + .remove = altr_i2c_remove, + .driver = { + .name = "altera-i2c", + .of_match_table = altr_i2c_of_match, + }, +}; + +module_platform_driver(altr_i2c_driver); + +MODULE_DESCRIPTION("Altera Soft IP I2C bus driver"); +MODULE_AUTHOR("Thor Thayer <thor.thayer@xxxxxxxxxxxxxxx>"); +MODULE_LICENSE("GPL v2"); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
