diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-ocores.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-ocores.c | 308 |
1 files changed, 260 insertions, 48 deletions
diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c index 87f9caacba85..4e1a077fb688 100644 --- a/drivers/i2c/busses/i2c-ocores.c +++ b/drivers/i2c/busses/i2c-ocores.c @@ -1,3 +1,4 @@ +// SPDX-License-Identifier: GPL-2.0 /* * i2c-ocores.c: I2C bus driver for OpenCores I2C controller * (https://opencores.org/project/i2c/overview) @@ -6,13 +7,10 @@ * * Support for the GRLIB port of the controller by * Andreas Larsson <andreas@gaisler.com> - * - * This file is licensed under the terms of the GNU General Public License - * version 2. This program is licensed "as is" without any warranty of any - * kind, whether express or implied. */ #include <linux/clk.h> +#include <linux/delay.h> #include <linux/err.h> #include <linux/kernel.h> #include <linux/module.h> @@ -25,17 +23,28 @@ #include <linux/slab.h> #include <linux/io.h> #include <linux/log2.h> +#include <linux/spinlock.h> +#include <linux/jiffies.h> + +#define OCORES_FLAG_POLL BIT(0) +/* + * 'process_lock' exists because ocores_process() and ocores_process_timeout() + * can't run in parallel. + */ struct ocores_i2c { void __iomem *base; + int iobase; u32 reg_shift; u32 reg_io_width; + unsigned long flags; wait_queue_head_t wait; struct i2c_adapter adap; struct i2c_msg *msg; int pos; int nmsgs; int state; /* see STATE_ */ + spinlock_t process_lock; struct clk *clk; int ip_clock_khz; int bus_clock_khz; @@ -127,6 +136,16 @@ static inline u8 oc_getreg_32be(struct ocores_i2c *i2c, int reg) return ioread32be(i2c->base + (reg << i2c->reg_shift)); } +static void oc_setreg_io_8(struct ocores_i2c *i2c, int reg, u8 value) +{ + outb(value, i2c->iobase + reg); +} + +static inline u8 oc_getreg_io_8(struct ocores_i2c *i2c, int reg) +{ + return inb(i2c->iobase + reg); +} + static inline void oc_setreg(struct ocores_i2c *i2c, int reg, u8 value) { i2c->setreg(i2c, reg, value); @@ -137,23 +156,29 @@ static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg) return i2c->getreg(i2c, reg); } -static void ocores_process(struct ocores_i2c *i2c) +static void ocores_process(struct ocores_i2c *i2c, u8 stat) { struct i2c_msg *msg = i2c->msg; - u8 stat = oc_getreg(i2c, OCI2C_STATUS); + unsigned long flags; + + /* + * If we spin here is because we are in timeout, so we are going + * to be in STATE_ERROR. See ocores_process_timeout() + */ + spin_lock_irqsave(&i2c->process_lock, flags); if ((i2c->state == STATE_DONE) || (i2c->state == STATE_ERROR)) { /* stop has been sent */ oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK); wake_up(&i2c->wait); - return; + goto out; } /* error? */ if (stat & OCI2C_STAT_ARBLOST) { i2c->state = STATE_ERROR; oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP); - return; + goto out; } if ((i2c->state == STATE_START) || (i2c->state == STATE_WRITE)) { @@ -163,10 +188,11 @@ static void ocores_process(struct ocores_i2c *i2c) if (stat & OCI2C_STAT_NACK) { i2c->state = STATE_ERROR; oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP); - return; + goto out; } - } else + } else { msg->buf[i2c->pos++] = oc_getreg(i2c, OCI2C_DATA); + } /* end of msg? */ if (i2c->pos == msg->len) { @@ -183,15 +209,15 @@ static void ocores_process(struct ocores_i2c *i2c) i2c->state = STATE_START; oc_setreg(i2c, OCI2C_DATA, addr); - oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START); - return; - } else - i2c->state = (msg->flags & I2C_M_RD) - ? STATE_READ : STATE_WRITE; + oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START); + goto out; + } + i2c->state = (msg->flags & I2C_M_RD) + ? STATE_READ : STATE_WRITE; } else { i2c->state = STATE_DONE; oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP); - return; + goto out; } } @@ -202,20 +228,148 @@ static void ocores_process(struct ocores_i2c *i2c) oc_setreg(i2c, OCI2C_DATA, msg->buf[i2c->pos++]); oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_WRITE); } + +out: + spin_unlock_irqrestore(&i2c->process_lock, flags); } static irqreturn_t ocores_isr(int irq, void *dev_id) { struct ocores_i2c *i2c = dev_id; + u8 stat = oc_getreg(i2c, OCI2C_STATUS); + + if (!(stat & OCI2C_STAT_IF)) + return IRQ_NONE; - ocores_process(i2c); + ocores_process(i2c, stat); return IRQ_HANDLED; } -static int ocores_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) +/** + * Process timeout event + * @i2c: ocores I2C device instance + */ +static void ocores_process_timeout(struct ocores_i2c *i2c) { - struct ocores_i2c *i2c = i2c_get_adapdata(adap); + unsigned long flags; + + spin_lock_irqsave(&i2c->process_lock, flags); + i2c->state = STATE_ERROR; + oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP); + spin_unlock_irqrestore(&i2c->process_lock, flags); +} + +/** + * Wait until something change in a given register + * @i2c: ocores I2C device instance + * @reg: register to query + * @mask: bitmask to apply on register value + * @val: expected result + * @timeout: timeout in jiffies + * + * Timeout is necessary to avoid to stay here forever when the chip + * does not answer correctly. + * + * Return: 0 on success, -ETIMEDOUT on timeout + */ +static int ocores_wait(struct ocores_i2c *i2c, + int reg, u8 mask, u8 val, + const unsigned long timeout) +{ + unsigned long j; + + j = jiffies + timeout; + while (1) { + u8 status = oc_getreg(i2c, reg); + + if ((status & mask) == val) + break; + + if (time_after(jiffies, j)) + return -ETIMEDOUT; + } + return 0; +} + +/** + * Wait until is possible to process some data + * @i2c: ocores I2C device instance + * + * Used when the device is in polling mode (interrupts disabled). + * + * Return: 0 on success, -ETIMEDOUT on timeout + */ +static int ocores_poll_wait(struct ocores_i2c *i2c) +{ + u8 mask; + int err; + + if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) { + /* transfer is over */ + mask = OCI2C_STAT_BUSY; + } else { + /* on going transfer */ + mask = OCI2C_STAT_TIP; + /* + * We wait for the data to be transferred (8bit), + * then we start polling on the ACK/NACK bit + */ + udelay((8 * 1000) / i2c->bus_clock_khz); + } + + /* + * once we are here we expect to get the expected result immediately + * so if after 1ms we timeout then something is broken. + */ + err = ocores_wait(i2c, OCI2C_STATUS, mask, 0, msecs_to_jiffies(1)); + if (err) + dev_warn(i2c->adap.dev.parent, + "%s: STATUS timeout, bit 0x%x did not clear in 1ms\n", + __func__, mask); + return err; +} + +/** + * It handles an IRQ-less transfer + * @i2c: ocores I2C device instance + * + * Even if IRQ are disabled, the I2C OpenCore IP behavior is exactly the same + * (only that IRQ are not produced). This means that we can re-use entirely + * ocores_isr(), we just add our polling code around it. + * + * It can run in atomic context + */ +static void ocores_process_polling(struct ocores_i2c *i2c) +{ + while (1) { + irqreturn_t ret; + int err; + + err = ocores_poll_wait(i2c); + if (err) { + i2c->state = STATE_ERROR; + break; /* timeout */ + } + + ret = ocores_isr(-1, i2c); + if (ret == IRQ_NONE) + break; /* all messages have been transferred */ + } +} + +static int ocores_xfer_core(struct ocores_i2c *i2c, + struct i2c_msg *msgs, int num, + bool polling) +{ + int ret; + u8 ctrl; + + ctrl = oc_getreg(i2c, OCI2C_CONTROL); + if (polling) + oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~OCI2C_CTRL_IEN); + else + oc_setreg(i2c, OCI2C_CONTROL, ctrl | OCI2C_CTRL_IEN); i2c->msg = msgs; i2c->pos = 0; @@ -225,11 +379,35 @@ static int ocores_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) oc_setreg(i2c, OCI2C_DATA, i2c_8bit_addr_from_msg(i2c->msg)); oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START); - if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) || - (i2c->state == STATE_DONE), HZ)) - return (i2c->state == STATE_DONE) ? num : -EIO; - else - return -ETIMEDOUT; + if (polling) { + ocores_process_polling(i2c); + } else { + ret = wait_event_timeout(i2c->wait, + (i2c->state == STATE_ERROR) || + (i2c->state == STATE_DONE), HZ); + if (ret == 0) { + ocores_process_timeout(i2c); + return -ETIMEDOUT; + } + } + + return (i2c->state == STATE_DONE) ? num : -EIO; +} + +static int ocores_xfer_polling(struct i2c_adapter *adap, + struct i2c_msg *msgs, int num) +{ + return ocores_xfer_core(i2c_get_adapdata(adap), msgs, num, true); +} + +static int ocores_xfer(struct i2c_adapter *adap, + struct i2c_msg *msgs, int num) +{ + struct ocores_i2c *i2c = i2c_get_adapdata(adap); + + if (i2c->flags & OCORES_FLAG_POLL) + return ocores_xfer_polling(adap, msgs, num); + return ocores_xfer_core(i2c, msgs, num, false); } static int ocores_init(struct device *dev, struct ocores_i2c *i2c) @@ -239,7 +417,8 @@ static int ocores_init(struct device *dev, struct ocores_i2c *i2c) u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL); /* make sure the device is disabled */ - oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN)); + ctrl &= ~(OCI2C_CTRL_EN | OCI2C_CTRL_IEN); + oc_setreg(i2c, OCI2C_CONTROL, ctrl); prescale = (i2c->ip_clock_khz / (5 * i2c->bus_clock_khz)) - 1; prescale = clamp(prescale, 0, 0xffff); @@ -257,7 +436,7 @@ static int ocores_init(struct device *dev, struct ocores_i2c *i2c) /* Init the device */ oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK); - oc_setreg(i2c, OCI2C_CONTROL, ctrl | OCI2C_CTRL_IEN | OCI2C_CTRL_EN); + oc_setreg(i2c, OCI2C_CONTROL, ctrl | OCI2C_CTRL_EN); return 0; } @@ -294,13 +473,16 @@ static const struct of_device_id ocores_i2c_match[] = { MODULE_DEVICE_TABLE(of, ocores_i2c_match); #ifdef CONFIG_OF -/* Read and write functions for the GRLIB port of the controller. Registers are +/* + * Read and write functions for the GRLIB port of the controller. Registers are * 32-bit big endian and the PRELOW and PREHIGH registers are merged into one - * register. The subsequent registers has their offset decreased accordingly. */ + * register. The subsequent registers have their offsets decreased accordingly. + */ static u8 oc_getreg_grlib(struct ocores_i2c *i2c, int reg) { u32 rd; int rreg = reg; + if (reg != OCI2C_PRELOW) rreg--; rd = ioread32be(i2c->base + (rreg << i2c->reg_shift)); @@ -314,6 +496,7 @@ static void oc_setreg_grlib(struct ocores_i2c *i2c, int reg, u8 value) { u32 curr, wr; int rreg = reg; + if (reg != OCI2C_PRELOW) rreg--; if (reg == OCI2C_PRELOW || reg == OCI2C_PREHIGH) { @@ -402,7 +585,7 @@ static int ocores_i2c_of_probe(struct platform_device *pdev, return 0; } #else -#define ocores_i2c_of_probe(pdev,i2c) -ENODEV +#define ocores_i2c_of_probe(pdev, i2c) -ENODEV #endif static int ocores_i2c_probe(struct platform_device *pdev) @@ -414,25 +597,41 @@ static int ocores_i2c_probe(struct platform_device *pdev) int ret; int i; - irq = platform_get_irq(pdev, 0); - if (irq < 0) - return irq; - i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL); if (!i2c) return -ENOMEM; + spin_lock_init(&i2c->process_lock); + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); - i2c->base = devm_ioremap_resource(&pdev->dev, res); - if (IS_ERR(i2c->base)) - return PTR_ERR(i2c->base); + if (res) { + i2c->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(i2c->base)) + return PTR_ERR(i2c->base); + } else { + res = platform_get_resource(pdev, IORESOURCE_IO, 0); + if (!res) + return -EINVAL; + i2c->iobase = res->start; + if (!devm_request_region(&pdev->dev, res->start, + resource_size(res), + pdev->name)) { + dev_err(&pdev->dev, "Can't get I/O resource.\n"); + return -EBUSY; + } + i2c->setreg = oc_setreg_io_8; + i2c->getreg = oc_getreg_io_8; + } pdata = dev_get_platdata(&pdev->dev); if (pdata) { i2c->reg_shift = pdata->reg_shift; i2c->reg_io_width = pdata->reg_io_width; i2c->ip_clock_khz = pdata->clock_khz; - i2c->bus_clock_khz = 100; + if (pdata->bus_khz) + i2c->bus_clock_khz = pdata->bus_khz; + else + i2c->bus_clock_khz = 100; } else { ret = ocores_i2c_of_probe(pdev, i2c); if (ret) @@ -470,18 +669,29 @@ static int ocores_i2c_probe(struct platform_device *pdev) } } + init_waitqueue_head(&i2c->wait); + + irq = platform_get_irq(pdev, 0); + if (irq == -ENXIO) { + i2c->flags |= OCORES_FLAG_POLL; + } else { + if (irq < 0) + return irq; + } + + if (!(i2c->flags & OCORES_FLAG_POLL)) { + ret = devm_request_irq(&pdev->dev, irq, ocores_isr, 0, + pdev->name, i2c); + if (ret) { + dev_err(&pdev->dev, "Cannot claim IRQ\n"); + goto err_clk; + } + } + ret = ocores_init(&pdev->dev, i2c); if (ret) goto err_clk; - init_waitqueue_head(&i2c->wait); - ret = devm_request_irq(&pdev->dev, irq, ocores_isr, 0, - pdev->name, i2c); - if (ret) { - dev_err(&pdev->dev, "Cannot claim IRQ\n"); - goto err_clk; - } - /* hook up driver to tree */ platform_set_drvdata(pdev, i2c); i2c->adap = ocores_adapter; @@ -510,10 +720,11 @@ err_clk: static int ocores_i2c_remove(struct platform_device *pdev) { struct ocores_i2c *i2c = platform_get_drvdata(pdev); + u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL); /* disable i2c logic */ - oc_setreg(i2c, OCI2C_CONTROL, oc_getreg(i2c, OCI2C_CONTROL) - & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN)); + ctrl &= ~(OCI2C_CTRL_EN | OCI2C_CTRL_IEN); + oc_setreg(i2c, OCI2C_CONTROL, ctrl); /* remove adapter & data */ i2c_del_adapter(&i2c->adap); @@ -531,7 +742,8 @@ static int ocores_i2c_suspend(struct device *dev) u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL); /* make sure the device is disabled */ - oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN)); + ctrl &= ~(OCI2C_CTRL_EN | OCI2C_CTRL_IEN); + oc_setreg(i2c, OCI2C_CONTROL, ctrl); if (!IS_ERR(i2c->clk)) clk_disable_unprepare(i2c->clk); |