--- /dev/null
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * ocores-i2c.c: I2C bus driver for OpenCores I2C controller
+ * (https://opencores.org/projects/i2c)
+ *
+ * (C) Copyright Peter Korsgaard <peter@korsgaard.com>
+ *
+ * Copyright (C) 2020 SiFive, Inc.
+ * Pragnesh Patel <pragnesh.patel@sifive.com>
+ *
+ * Support for the GRLIB port of the controller by
+ * Andreas Larsson <andreas@gaisler.com>
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <clk.h>
+#include <dm.h>
+#include <dm/device_compat.h>
+#include <i2c.h>
+#include <linux/io.h>
+#include <linux/compat.h>
+#include <linux/log2.h>
+#include <linux/delay.h>
+
+/* 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 */
+
+struct ocores_i2c_bus {
+ void __iomem *base;
+ u32 reg_shift;
+ u32 reg_io_width;
+ unsigned long flags;
+ struct i2c_msg *msg;
+ int pos;
+ int nmsgs;
+ int state; /* see STATE_ */
+ struct clk clk;
+ int ip_clk_khz;
+ int bus_clk_khz;
+ void (*setreg)(struct ocores_i2c_bus *i2c, int reg, u8 value);
+ u8 (*getreg)(struct ocores_i2c_bus *i2c, int reg);
+};
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/* Boolean attribute values */
+enum {
+ FALSE = 0,
+ TRUE,
+};
+
+static void oc_setreg_8(struct ocores_i2c_bus *i2c, int reg, u8 value)
+{
+ writeb(value, i2c->base + (reg << i2c->reg_shift));
+}
+
+static void oc_setreg_16(struct ocores_i2c_bus *i2c, int reg, u8 value)
+{
+ writew(value, i2c->base + (reg << i2c->reg_shift));
+}
+
+static void oc_setreg_32(struct ocores_i2c_bus *i2c, int reg, u8 value)
+{
+ writel(value, i2c->base + (reg << i2c->reg_shift));
+}
+
+static void oc_setreg_16be(struct ocores_i2c_bus *i2c, int reg, u8 value)
+{
+ out_be16(i2c->base + (reg << i2c->reg_shift), value);
+}
+
+static void oc_setreg_32be(struct ocores_i2c_bus *i2c, int reg, u8 value)
+{
+ out_be32(i2c->base + (reg << i2c->reg_shift), value);
+}
+
+static inline u8 oc_getreg_8(struct ocores_i2c_bus *i2c, int reg)
+{
+ return readb(i2c->base + (reg << i2c->reg_shift));
+}
+
+static inline u8 oc_getreg_16(struct ocores_i2c_bus *i2c, int reg)
+{
+ return readw(i2c->base + (reg << i2c->reg_shift));
+}
+
+static inline u8 oc_getreg_32(struct ocores_i2c_bus *i2c, int reg)
+{
+ return readl(i2c->base + (reg << i2c->reg_shift));
+}
+
+static inline u8 oc_getreg_16be(struct ocores_i2c_bus *i2c, int reg)
+{
+ return in_be16(i2c->base + (reg << i2c->reg_shift));
+}
+
+static inline u8 oc_getreg_32be(struct ocores_i2c_bus *i2c, int reg)
+{
+ return in_be32(i2c->base + (reg << i2c->reg_shift));
+}
+
+static inline void oc_setreg(struct ocores_i2c_bus *i2c, int reg, u8 value)
+{
+ i2c->setreg(i2c, reg, value);
+}
+
+static inline u8 oc_getreg(struct ocores_i2c_bus *i2c, int reg)
+{
+ return i2c->getreg(i2c, reg);
+}
+
+static inline u8 i2c_8bit_addr_from_msg(const struct i2c_msg *msg)
+{
+ return (msg->addr << 1) | (msg->flags & I2C_M_RD ? 1 : 0);
+}
+
+static void ocores_process(struct ocores_i2c_bus *i2c, u8 stat)
+{
+ struct i2c_msg *msg = i2c->msg;
+
+ if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) {
+ /* stop has been sent */
+ oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK);
+ return;
+ }
+
+ /* error? */
+ if (stat & OCI2C_STAT_ARBLOST) {
+ i2c->state = STATE_ERROR;
+ oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
+ return;
+ }
+
+ 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);
+ return;
+ }
+ } 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);
+ return;
+ }
+ 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;
+ }
+ }
+
+ 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);
+ }
+}
+
+static irqreturn_t ocores_isr(int irq, void *dev_id)
+{
+ struct ocores_i2c_bus *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;
+}
+
+/**
+ * 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
+ * @msec: timeout in msec
+ *
+ * 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_bus *i2c,
+ int reg, u8 mask, u8 val,
+ const unsigned long msec)
+{
+ u32 count = 0;
+
+ while (1) {
+ u8 status = oc_getreg(i2c, reg);
+
+ if ((status & mask) == val)
+ break;
+
+ udelay(1);
+ count += 1;
+
+ if (count == (1000 * msec))
+ 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_bus *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_clk_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, 1);
+ if (err)
+ debug("%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_bus *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 */
+ } else {
+ if (i2c->flags & OCORES_FLAG_BROKEN_IRQ)
+ if (i2c->state == STATE_DONE)
+ break;
+ }
+ }
+}
+
+static int ocores_xfer_core(struct ocores_i2c_bus *i2c,
+ struct i2c_msg *msgs, int num, bool polling)
+{
+ u8 ctrl;
+
+ ctrl = oc_getreg(i2c, OCI2C_CONTROL);
+
+ if (polling)
+ 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)
+ ocores_process_polling(i2c);
+
+ return (i2c->state == STATE_DONE) ? num : -EIO;
+}
+
+static int ocores_i2c_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
+{
+ struct ocores_i2c_bus *bus = dev_get_priv(dev);
+ int ret;
+
+ debug("i2c_xfer: %d messages\n", nmsgs);
+
+ ret = ocores_xfer_core(bus, msg, nmsgs, 1);
+
+ if (ret != nmsgs) {
+ debug("i2c_write: error sending\n");
+ return -EREMOTEIO;
+ }
+
+ return 0;
+}
+
+static int ocores_i2c_enable_clk(struct udevice *dev)
+{
+ struct ocores_i2c_bus *bus = dev_get_priv(dev);
+ ulong clk_rate;
+ int ret;
+
+ ret = clk_get_by_index(dev, 0, &bus->clk);
+ if (ret)
+ return -EINVAL;
+
+ ret = clk_enable(&bus->clk);
+ if (ret)
+ return ret;
+
+ clk_rate = clk_get_rate(&bus->clk);
+ if (!clk_rate)
+ return -EINVAL;
+
+ bus->ip_clk_khz = clk_rate / 1000;
+
+ clk_free(&bus->clk);
+
+ return 0;
+}
+
+static int ocores_init(struct udevice *dev, struct ocores_i2c_bus *bus)
+{
+ int prescale;
+ int diff;
+ u8 ctrl = oc_getreg(bus, OCI2C_CONTROL);
+
+ /* make sure the device is disabled */
+ ctrl &= ~(OCI2C_CTRL_EN | OCI2C_CTRL_IEN);
+ oc_setreg(bus, OCI2C_CONTROL, ctrl);
+
+ prescale = (bus->ip_clk_khz / (5 * bus->bus_clk_khz)) - 1;
+ prescale = clamp(prescale, 0, 0xffff);
+
+ diff = bus->ip_clk_khz / (5 * (prescale + 1)) - bus->bus_clk_khz;
+ if (abs(diff) > bus->bus_clk_khz / 10) {
+ debug("Unsupported clock settings: core: %d KHz, bus: %d KHz\n",
+ bus->ip_clk_khz, bus->bus_clk_khz);
+ return -EINVAL;
+ }
+
+ oc_setreg(bus, OCI2C_PRELOW, prescale & 0xff);
+ oc_setreg(bus, OCI2C_PREHIGH, prescale >> 8);
+
+ /* Init the device */
+ oc_setreg(bus, OCI2C_CMD, OCI2C_CMD_IACK);
+ oc_setreg(bus, OCI2C_CONTROL, ctrl | OCI2C_CTRL_EN);
+
+ return 0;
+}
+
+/*
+ * 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_bus *i2c, int reg)
+{
+ u32 rd;
+ int rreg = reg;
+
+ if (reg != OCI2C_PRELOW)
+ rreg--;
+ rd = in_be32(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_bus *i2c, int reg, u8 value)
+{
+ u32 curr, wr;
+ int rreg = reg;
+
+ if (reg != OCI2C_PRELOW)
+ rreg--;
+ if (reg == OCI2C_PRELOW || reg == OCI2C_PREHIGH) {
+ curr = in_be32(i2c->base + (rreg << i2c->reg_shift));
+ if (reg == OCI2C_PRELOW)
+ wr = (curr & 0xff00) | value;
+ else
+ wr = (((u32)value) << 8) | (curr & 0xff);
+ } else {
+ wr = value;
+ }
+ out_be32(i2c->base + (rreg << i2c->reg_shift), wr);
+}
+
+static int ocores_i2c_set_bus_speed(struct udevice *dev, unsigned int speed)
+{
+ int prescale;
+ int diff;
+ struct ocores_i2c_bus *bus = dev_get_priv(dev);
+
+ /* speed in Khz */
+ speed = speed / 1000;
+
+ prescale = (bus->ip_clk_khz / (5 * speed)) - 1;
+ prescale = clamp(prescale, 0, 0xffff);
+
+ diff = bus->ip_clk_khz / (5 * (prescale + 1)) - speed;
+ if (abs(diff) > speed / 10) {
+ debug("Unsupported clock settings: core: %d KHz, bus: %d KHz\n",
+ bus->ip_clk_khz, speed);
+ return -EINVAL;
+ }
+
+ oc_setreg(bus, OCI2C_PRELOW, prescale & 0xff);
+ oc_setreg(bus, OCI2C_PREHIGH, prescale >> 8);
+
+ bus->bus_clk_khz = speed;
+ return 0;
+}
+
+int ocores_i2c_get_bus_speed(struct udevice *dev)
+{
+ struct ocores_i2c_bus *bus = dev_get_priv(dev);
+
+ return (bus->bus_clk_khz * 1000);
+}
+
+static const struct dm_i2c_ops ocores_i2c_ops = {
+ .xfer = ocores_i2c_xfer,
+ .set_bus_speed = ocores_i2c_set_bus_speed,
+ .get_bus_speed = ocores_i2c_get_bus_speed,
+};
+
+static int ocores_i2c_probe(struct udevice *dev)
+{
+ struct ocores_i2c_bus *bus = dev_get_priv(dev);
+ bool clock_frequency_present;
+ u32 val;
+ u32 clock_frequency_khz;
+ int ret;
+
+ bus->base = (void __iomem *)devfdt_get_addr(dev);
+
+ if (dev_read_u32(dev, "reg-shift", &bus->reg_shift)) {
+ /* no 'reg-shift', check for deprecated 'regstep' */
+ ret = dev_read_u32(dev, "regstep", &val);
+ if (ret) {
+ dev_err(dev,
+ "missing both reg-shift and regstep property: %d\n", ret);
+ return -EINVAL;
+ } else {
+ bus->reg_shift = ilog2(val);
+ dev_warn(dev,
+ "regstep property deprecated, use reg-shift\n");
+ }
+ }
+
+ if (dev_read_u32(dev, "clock-frequency", &val)) {
+ bus->bus_clk_khz = 100;
+ clock_frequency_present = FALSE;
+ } else {
+ bus->bus_clk_khz = val / 1000;
+ clock_frequency_khz = val / 1000;
+ clock_frequency_present = TRUE;
+ }
+
+ ret = ocores_i2c_enable_clk(dev);
+ if (ret)
+ return ret;
+
+ if (bus->ip_clk_khz == 0) {
+ if (dev_read_u32(dev, "opencores,ip-clock-frequency", &val)) {
+ if (!clock_frequency_present) {
+ dev_err(dev,
+ "Missing required parameter 'opencores,ip-clock-frequency'\n");
+ clk_disable(&bus->clk);
+ return -ENODEV;
+ }
+
+ bus->ip_clk_khz = clock_frequency_khz;
+ dev_warn(dev,
+ "Deprecated usage of the 'clock-frequency' property, please update to 'opencores,ip-clock-frequency'\n");
+ } else {
+ bus->ip_clk_khz = val / 1000;
+ if (clock_frequency_present)
+ bus->bus_clk_khz = clock_frequency_khz;
+ }
+ }
+
+ bus->reg_io_width = dev_read_u32_default(dev, "reg-io-width", 1);
+
+ if (dev_get_driver_data(dev) == TYPE_GRLIB) {
+ debug("GRLIB variant of i2c-ocores\n");
+ bus->setreg = oc_setreg_grlib;
+ bus->getreg = oc_getreg_grlib;
+ }
+
+ if (!bus->setreg || !bus->getreg) {
+ bool be = (cpu_to_be32(0x12345678) == 0x12345678);
+
+ switch (bus->reg_io_width) {
+ case 1:
+ bus->setreg = oc_setreg_8;
+ bus->getreg = oc_getreg_8;
+ break;
+
+ case 2:
+ bus->setreg = be ? oc_setreg_16be : oc_setreg_16;
+ bus->getreg = be ? oc_getreg_16be : oc_getreg_16;
+ break;
+
+ case 4:
+ bus->setreg = be ? oc_setreg_32be : oc_setreg_32;
+ bus->getreg = be ? oc_getreg_32be : oc_getreg_32;
+ break;
+
+ default:
+ debug("Unsupported I/O width (%d)\n",
+ bus->reg_io_width);
+ ret = -EINVAL;
+ goto err_clk;
+ }
+ }
+
+ /*
+ * Set OCORES_FLAG_BROKEN_IRQ to enable workaround for
+ * FU540-C000 SoC in polling mode.
+ * 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 (device_is_compatible(dev, "sifive,fu540-c000-i2c"))
+ bus->flags |= OCORES_FLAG_BROKEN_IRQ;
+
+ ret = ocores_init(dev, bus);
+ if (ret)
+ goto err_clk;
+
+ return 0;
+
+err_clk:
+ clk_disable(&bus->clk);
+ return ret;
+}
+
+static const struct udevice_id ocores_i2c_ids[] = {
+{ .compatible = "opencores,i2c-ocores", .data = TYPE_OCORES },
+{ .compatible = "aeroflexgaisler,i2cmst", .data = TYPE_GRLIB },
+{ .compatible = "sifive,fu540-c000-i2c" },
+{ .compatible = "sifive,i2c0" },
+};
+
+U_BOOT_DRIVER(i2c_ocores) = {
+ .name = "i2c_ocores",
+ .id = UCLASS_I2C,
+ .of_match = ocores_i2c_ids,
+ .probe = ocores_i2c_probe,
+ .priv_auto_alloc_size = sizeof(struct ocores_i2c_bus),
+ .ops = &ocores_i2c_ops,
+};
projects / u-boot.git / commitdiff