// SPDX-License-Identifier: GPL-2.0 /* * i2c-ocores.c: I2C bus driver for OpenCores I2C controller * (https://opencores.org/project/i2c/overview) * * Peter Korsgaard * * Support for the GRLIB port of the controller by * Andreas Larsson */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * 'process_lock' exists because ocores_process() and ocores_process_timeout() * can't run in parallel. */ struct ocores_i2c { void __iomem *base; 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; void (*setreg)(struct ocores_i2c *i2c, int reg, u8 value); u8 (*getreg)(struct ocores_i2c *i2c, int reg); }; /* registers */ #define OCI2C_PRELOW 0 #define OCI2C_PREHIGH 1 #define OCI2C_CONTROL 2 #define OCI2C_DATA 3 #define OCI2C_CMD 4 /* write only */ #define OCI2C_STATUS 4 /* read only, same address as OCI2C_CMD */ #define OCI2C_CTRL_IEN 0x40 #define OCI2C_CTRL_EN 0x80 #define OCI2C_CMD_START 0x91 #define OCI2C_CMD_STOP 0x41 #define OCI2C_CMD_READ 0x21 #define OCI2C_CMD_WRITE 0x11 #define OCI2C_CMD_READ_ACK 0x21 #define OCI2C_CMD_READ_NACK 0x29 #define OCI2C_CMD_IACK 0x01 #define OCI2C_STAT_IF 0x01 #define OCI2C_STAT_TIP 0x02 #define OCI2C_STAT_ARBLOST 0x20 #define OCI2C_STAT_BUSY 0x40 #define OCI2C_STAT_NACK 0x80 #define STATE_DONE 0 #define STATE_START 1 #define STATE_WRITE 2 #define STATE_READ 3 #define STATE_ERROR 4 #define TYPE_OCORES 0 #define TYPE_GRLIB 1 #define OCORES_FLAG_BROKEN_IRQ BIT(1) /* Broken IRQ for FU540-C000 SoC */ static void oc_setreg_8(struct ocores_i2c *i2c, int reg, u8 value) { iowrite8(value, i2c->base + (reg << i2c->reg_shift)); } static void oc_setreg_16(struct ocores_i2c *i2c, int reg, u8 value) { iowrite16(value, i2c->base + (reg << i2c->reg_shift)); } static void oc_setreg_32(struct ocores_i2c *i2c, int reg, u8 value) { iowrite32(value, i2c->base + (reg << i2c->reg_shift)); } static void oc_setreg_16be(struct ocores_i2c *i2c, int reg, u8 value) { iowrite16be(value, i2c->base + (reg << i2c->reg_shift)); } static void oc_setreg_32be(struct ocores_i2c *i2c, int reg, u8 value) { iowrite32be(value, i2c->base + (reg << i2c->reg_shift)); } static inline u8 oc_getreg_8(struct ocores_i2c *i2c, int reg) { return ioread8(i2c->base + (reg << i2c->reg_shift)); } static inline u8 oc_getreg_16(struct ocores_i2c *i2c, int reg) { return ioread16(i2c->base + (reg << i2c->reg_shift)); } static inline u8 oc_getreg_32(struct ocores_i2c *i2c, int reg) { return ioread32(i2c->base + (reg << i2c->reg_shift)); } static inline u8 oc_getreg_16be(struct ocores_i2c *i2c, int reg) { return ioread16be(i2c->base + (reg << i2c->reg_shift)); } static inline u8 oc_getreg_32be(struct ocores_i2c *i2c, int reg) { return ioread32be(i2c->base + (reg << i2c->reg_shift)); } static inline void oc_setreg(struct ocores_i2c *i2c, int reg, u8 value) { i2c->setreg(i2c, reg, value); } static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg) { return i2c->getreg(i2c, reg); } static void ocores_process(struct ocores_i2c *i2c, u8 stat) { struct i2c_msg *msg = i2c->msg; 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); goto out; } /* error? */ if (stat & OCI2C_STAT_ARBLOST) { i2c->state = STATE_ERROR; oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP); goto out; } if ((i2c->state == STATE_START) || (i2c->state == STATE_WRITE)) { i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE; if (stat & OCI2C_STAT_NACK) { i2c->state = STATE_ERROR; oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP); goto out; } } else { msg->buf[i2c->pos++] = oc_getreg(i2c, OCI2C_DATA); } /* end of msg? */ if (i2c->pos == msg->len) { i2c->nmsgs--; i2c->msg++; i2c->pos = 0; msg = i2c->msg; if (i2c->nmsgs) { /* end? */ /* send start? */ if (!(msg->flags & I2C_M_NOSTART)) { u8 addr = i2c_8bit_addr_from_msg(msg); i2c->state = STATE_START; oc_setreg(i2c, OCI2C_DATA, addr); 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); goto out; } } if (i2c->state == STATE_READ) { oc_setreg(i2c, OCI2C_CMD, i2c->pos == (msg->len-1) ? OCI2C_CMD_READ_NACK : OCI2C_CMD_READ_ACK); } else { 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 (i2c->flags & OCORES_FLAG_BROKEN_IRQ) { if ((stat & OCI2C_STAT_IF) && !(stat & OCI2C_STAT_BUSY)) return IRQ_NONE; } else if (!(stat & OCI2C_STAT_IF)) { return IRQ_NONE; } ocores_process(i2c, stat); return IRQ_HANDLED; } /** * ocores_process_timeout() - Process timeout event * @i2c: ocores I2C device instance */ static void ocores_process_timeout(struct ocores_i2c *i2c) { 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); } /** * ocores_wait() - 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; } /** * ocores_poll_wait() - 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; } /** * ocores_process_polling() - 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 * * Return: 0 on success, -ETIMEDOUT on timeout */ static int ocores_process_polling(struct ocores_i2c *i2c) { irqreturn_t ret; int err = 0; while (1) { err = ocores_poll_wait(i2c); if (err) break; /* timeout */ ret = ocores_isr(-1, i2c); if (ret == IRQ_NONE) break; /* all messages have been transferred */ else { if (i2c->flags & OCORES_FLAG_BROKEN_IRQ) if (i2c->state == STATE_DONE) break; } } return err; } static int ocores_xfer_core(struct ocores_i2c *i2c, struct i2c_msg *msgs, int num, bool polling) { int ret = 0; 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; i2c->nmsgs = num; i2c->state = STATE_START; oc_setreg(i2c, OCI2C_DATA, i2c_8bit_addr_from_msg(i2c->msg)); oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START); if (polling) { ret = ocores_process_polling(i2c); } else { if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) || (i2c->state == STATE_DONE), HZ) == 0) ret = -ETIMEDOUT; } if (ret) { ocores_process_timeout(i2c); return ret; } 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) { return ocores_xfer_core(i2c_get_adapdata(adap), msgs, num, false); } static int ocores_init(struct device *dev, struct ocores_i2c *i2c) { int prescale; int diff; u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL); /* make sure the device is disabled */ 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); diff = i2c->ip_clock_khz / (5 * (prescale + 1)) - i2c->bus_clock_khz; if (abs(diff) > i2c->bus_clock_khz / 10) { dev_err(dev, "Unsupported clock settings: core: %d KHz, bus: %d KHz\n", i2c->ip_clock_khz, i2c->bus_clock_khz); return -EINVAL; } oc_setreg(i2c, OCI2C_PRELOW, prescale & 0xff); oc_setreg(i2c, OCI2C_PREHIGH, prescale >> 8); /* Init the device */ oc_setreg(i2c, OCI2C_CONTROL, ctrl | OCI2C_CTRL_EN); oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK); return 0; } static u32 ocores_func(struct i2c_adapter *adap) { return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; } static struct i2c_algorithm ocores_algorithm = { .master_xfer = ocores_xfer, .master_xfer_atomic = ocores_xfer_polling, .functionality = ocores_func, }; static const struct i2c_adapter ocores_adapter = { .owner = THIS_MODULE, .name = "i2c-ocores", .class = I2C_CLASS_DEPRECATED, .algo = &ocores_algorithm, }; static const struct of_device_id ocores_i2c_match[] = { { .compatible = "opencores,i2c-ocores", .data = (void *)TYPE_OCORES, }, { .compatible = "aeroflexgaisler,i2cmst", .data = (void *)TYPE_GRLIB, }, { .compatible = "sifive,fu540-c000-i2c", }, { .compatible = "sifive,i2c0", }, {}, }; MODULE_DEVICE_TABLE(of, ocores_i2c_match); #ifdef CONFIG_OF /* * 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 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)); if (reg == OCI2C_PREHIGH) return (u8)(rd >> 8); else return (u8)rd; } 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) { curr = ioread32be(i2c->base + (rreg << i2c->reg_shift)); if (reg == OCI2C_PRELOW) wr = (curr & 0xff00) | value; else wr = (((u32)value) << 8) | (curr & 0xff); } else { wr = value; } iowrite32be(wr, i2c->base + (rreg << i2c->reg_shift)); } static int ocores_i2c_of_probe(struct platform_device *pdev, struct ocores_i2c *i2c) { struct device_node *np = pdev->dev.of_node; const struct of_device_id *match; u32 val; u32 clock_frequency; bool clock_frequency_present; if (of_property_read_u32(np, "reg-shift", &i2c->reg_shift)) { /* no 'reg-shift', check for deprecated 'regstep' */ if (!of_property_read_u32(np, "regstep", &val)) { if (!is_power_of_2(val)) { dev_err(&pdev->dev, "invalid regstep %d\n", val); return -EINVAL; } i2c->reg_shift = ilog2(val); dev_warn(&pdev->dev, "regstep property deprecated, use reg-shift\n"); } } clock_frequency_present = !of_property_read_u32(np, "clock-frequency", &clock_frequency); i2c->bus_clock_khz = 100; i2c->clk = devm_clk_get_optional_enabled(&pdev->dev, NULL); if (IS_ERR(i2c->clk)) return dev_err_probe(&pdev->dev, PTR_ERR(i2c->clk), "devm_clk_get_optional_enabled failed\n"); i2c->ip_clock_khz = clk_get_rate(i2c->clk) / 1000; if (clock_frequency_present) i2c->bus_clock_khz = clock_frequency / 1000; if (i2c->ip_clock_khz == 0) { if (of_property_read_u32(np, "opencores,ip-clock-frequency", &val)) { if (!clock_frequency_present) { dev_err(&pdev->dev, "Missing required parameter 'opencores,ip-clock-frequency'\n"); return -ENODEV; } i2c->ip_clock_khz = clock_frequency / 1000; dev_warn(&pdev->dev, "Deprecated usage of the 'clock-frequency' property, please update to 'opencores,ip-clock-frequency'\n"); } else { i2c->ip_clock_khz = val / 1000; if (clock_frequency_present) i2c->bus_clock_khz = clock_frequency / 1000; } } of_property_read_u32(pdev->dev.of_node, "reg-io-width", &i2c->reg_io_width); match = of_match_node(ocores_i2c_match, pdev->dev.of_node); if (match && (long)match->data == TYPE_GRLIB) { dev_dbg(&pdev->dev, "GRLIB variant of i2c-ocores\n"); i2c->setreg = oc_setreg_grlib; i2c->getreg = oc_getreg_grlib; } return 0; } #else #define ocores_i2c_of_probe(pdev, i2c) -ENODEV #endif static int ocores_i2c_probe(struct platform_device *pdev) { struct ocores_i2c *i2c; struct ocores_i2c_platform_data *pdata; struct resource *res; int irq; int ret; int i; 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); 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; 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->base = devm_ioport_map(&pdev->dev, res->start, resource_size(res)); if (!i2c->base) { dev_err(&pdev->dev, "Can't map I/O resource.\n"); return -EBUSY; } i2c->reg_io_width = 1; } 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; 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) return ret; } if (i2c->reg_io_width == 0) i2c->reg_io_width = 1; /* Set to default value */ if (!i2c->setreg || !i2c->getreg) { bool be = pdata ? pdata->big_endian : of_device_is_big_endian(pdev->dev.of_node); switch (i2c->reg_io_width) { case 1: i2c->setreg = oc_setreg_8; i2c->getreg = oc_getreg_8; break; case 2: i2c->setreg = be ? oc_setreg_16be : oc_setreg_16; i2c->getreg = be ? oc_getreg_16be : oc_getreg_16; break; case 4: i2c->setreg = be ? oc_setreg_32be : oc_setreg_32; i2c->getreg = be ? oc_getreg_32be : oc_getreg_32; break; default: dev_err(&pdev->dev, "Unsupported I/O width (%d)\n", i2c->reg_io_width); return -EINVAL; } } init_waitqueue_head(&i2c->wait); irq = platform_get_irq_optional(pdev, 0); /* * Since the SoC does have an interrupt, its DT has an interrupt * property - But this should be bypassed as the IRQ logic in this * SoC is broken. */ if (of_device_is_compatible(pdev->dev.of_node, "sifive,fu540-c000-i2c")) { i2c->flags |= OCORES_FLAG_BROKEN_IRQ; irq = -ENXIO; } if (irq == -ENXIO) { ocores_algorithm.master_xfer = ocores_xfer_polling; } else { if (irq < 0) return irq; } if (ocores_algorithm.master_xfer != ocores_xfer_polling) { ret = devm_request_any_context_irq(&pdev->dev, irq, ocores_isr, 0, pdev->name, i2c); if (ret) { dev_err(&pdev->dev, "Cannot claim IRQ\n"); return ret; } } ret = ocores_init(&pdev->dev, i2c); if (ret) return ret; /* hook up driver to tree */ platform_set_drvdata(pdev, i2c); i2c->adap = ocores_adapter; i2c_set_adapdata(&i2c->adap, i2c); i2c->adap.dev.parent = &pdev->dev; i2c->adap.dev.of_node = pdev->dev.of_node; /* add i2c adapter to i2c tree */ ret = i2c_add_adapter(&i2c->adap); if (ret) return ret; /* add in known devices to the bus */ if (pdata) { for (i = 0; i < pdata->num_devices; i++) i2c_new_client_device(&i2c->adap, pdata->devices + i); } return 0; } static void 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 */ ctrl &= ~(OCI2C_CTRL_EN | OCI2C_CTRL_IEN); oc_setreg(i2c, OCI2C_CONTROL, ctrl); /* remove adapter & data */ i2c_del_adapter(&i2c->adap); } static int ocores_i2c_suspend(struct device *dev) { struct ocores_i2c *i2c = dev_get_drvdata(dev); u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL); /* make sure the device is disabled */ ctrl &= ~(OCI2C_CTRL_EN | OCI2C_CTRL_IEN); oc_setreg(i2c, OCI2C_CONTROL, ctrl); clk_disable_unprepare(i2c->clk); return 0; } static int ocores_i2c_resume(struct device *dev) { struct ocores_i2c *i2c = dev_get_drvdata(dev); unsigned long rate; int ret; ret = clk_prepare_enable(i2c->clk); if (ret) return dev_err_probe(dev, ret, "clk_prepare_enable failed\n"); rate = clk_get_rate(i2c->clk) / 1000; if (rate) i2c->ip_clock_khz = rate; return ocores_init(dev, i2c); } static DEFINE_NOIRQ_DEV_PM_OPS(ocores_i2c_pm, ocores_i2c_suspend, ocores_i2c_resume); static struct platform_driver ocores_i2c_driver = { .probe = ocores_i2c_probe, .remove_new = ocores_i2c_remove, .driver = { .name = "ocores-i2c", .of_match_table = ocores_i2c_match, .pm = pm_sleep_ptr(&ocores_i2c_pm), }, }; module_platform_driver(ocores_i2c_driver); MODULE_AUTHOR("Peter Korsgaard "); MODULE_DESCRIPTION("OpenCores I2C bus driver"); MODULE_LICENSE("GPL"); MODULE_ALIAS("platform:ocores-i2c");