diff options
Diffstat (limited to 'drivers/i2c/i2c-uniphier.c')
| -rw-r--r-- | drivers/i2c/i2c-uniphier.c | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/drivers/i2c/i2c-uniphier.c b/drivers/i2c/i2c-uniphier.c new file mode 100644 index 0000000..64a9ed8 --- /dev/null +++ b/drivers/i2c/i2c-uniphier.c @@ -0,0 +1,227 @@ +/* + * Copyright (C) 2014 Panasonic Corporation + * Author: Masahiro Yamada <yamada.m@jp.panasonic.com> + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +#include <common.h> +#include <linux/types.h> +#include <asm/io.h> +#include <asm/errno.h> +#include <dm/device.h> +#include <dm/root.h> +#include <i2c.h> +#include <fdtdec.h> + +DECLARE_GLOBAL_DATA_PTR; + +struct uniphier_i2c_regs { + u32 dtrm; /* data transmission */ +#define I2C_DTRM_STA (1 << 10) +#define I2C_DTRM_STO (1 << 9) +#define I2C_DTRM_NACK (1 << 8) +#define I2C_DTRM_RD (1 << 0) + u32 drec; /* data reception */ +#define I2C_DREC_STS (1 << 12) +#define I2C_DREC_LRB (1 << 11) +#define I2C_DREC_LAB (1 << 9) + u32 myad; /* slave address */ + u32 clk; /* clock frequency control */ + u32 brst; /* bus reset */ +#define I2C_BRST_FOEN (1 << 1) +#define I2C_BRST_BRST (1 << 0) + u32 hold; /* hold time control */ + u32 bsts; /* bus status monitor */ + u32 noise; /* noise filter control */ + u32 setup; /* setup time control */ +}; + +#define IOBUS_FREQ 100000000 + +struct uniphier_i2c_dev { + struct uniphier_i2c_regs __iomem *regs; /* register base */ + unsigned long input_clk; /* master clock (Hz) */ + unsigned long wait_us; /* wait for every byte transfer (us) */ +}; + +static int uniphier_i2c_probe(struct udevice *dev) +{ + fdt_addr_t addr; + fdt_size_t size; + struct uniphier_i2c_dev *priv = dev_get_priv(dev); + + addr = fdtdec_get_addr_size(gd->fdt_blob, dev->of_offset, "reg", &size); + + priv->regs = map_sysmem(addr, size); + + if (!priv->regs) + return -ENOMEM; + + priv->input_clk = IOBUS_FREQ; + + /* deassert reset */ + writel(0x3, &priv->regs->brst); + + return 0; +} + +static int uniphier_i2c_remove(struct udevice *dev) +{ + struct uniphier_i2c_dev *priv = dev_get_priv(dev); + + unmap_sysmem(priv->regs); + + return 0; +} + +static int send_and_recv_byte(struct uniphier_i2c_dev *dev, u32 dtrm) +{ + writel(dtrm, &dev->regs->dtrm); + + /* + * This controller only provides interruption to inform the completion + * of each byte transfer. (No status register to poll it.) + * Unfortunately, U-Boot does not have a good support of interrupt. + * Wait for a while. + */ + udelay(dev->wait_us); + + return readl(&dev->regs->drec); +} + +static int send_byte(struct uniphier_i2c_dev *dev, u32 dtrm, bool *stop) +{ + int ret = 0; + u32 drec; + + drec = send_and_recv_byte(dev, dtrm); + + if (drec & I2C_DREC_LAB) { + debug("uniphier_i2c: bus arbitration failed\n"); + *stop = false; + ret = -EREMOTEIO; + } + if (drec & I2C_DREC_LRB) { + debug("uniphier_i2c: slave did not return ACK\n"); + ret = -EREMOTEIO; + } + return ret; +} + +static int uniphier_i2c_transmit(struct uniphier_i2c_dev *dev, uint addr, + uint len, const u8 *buf, bool *stop) +{ + int ret; + + debug("%s: addr = %x, len = %d\n", __func__, addr, len); + + ret = send_byte(dev, I2C_DTRM_STA | I2C_DTRM_NACK | addr << 1, stop); + if (ret < 0) + goto fail; + + while (len--) { + ret = send_byte(dev, I2C_DTRM_NACK | *buf++, stop); + if (ret < 0) + goto fail; + } + +fail: + if (*stop) + writel(I2C_DTRM_STO | I2C_DTRM_NACK, &dev->regs->dtrm); + + return ret; +} + +static int uniphier_i2c_receive(struct uniphier_i2c_dev *dev, uint addr, + uint len, u8 *buf, bool *stop) +{ + int ret; + + debug("%s: addr = %x, len = %d\n", __func__, addr, len); + + ret = send_byte(dev, I2C_DTRM_STA | I2C_DTRM_NACK | + I2C_DTRM_RD | addr << 1, stop); + if (ret < 0) + goto fail; + + while (len--) + *buf++ = send_and_recv_byte(dev, len ? 0 : I2C_DTRM_NACK); + +fail: + if (*stop) + writel(I2C_DTRM_STO | I2C_DTRM_NACK, &dev->regs->dtrm); + + return ret; +} + +static int uniphier_i2c_xfer(struct udevice *bus, struct i2c_msg *msg, + int nmsgs) +{ + int ret = 0; + struct uniphier_i2c_dev *dev = dev_get_priv(bus); + bool stop; + + for (; nmsgs > 0; nmsgs--, msg++) { + /* If next message is read, skip the stop condition */ + stop = nmsgs > 1 && msg[1].flags & I2C_M_RD ? false : true; + + if (msg->flags & I2C_M_RD) + ret = uniphier_i2c_receive(dev, msg->addr, msg->len, + msg->buf, &stop); + else + ret = uniphier_i2c_transmit(dev, msg->addr, msg->len, + msg->buf, &stop); + + if (ret < 0) + break; + } + + return ret; +} + +static int uniphier_i2c_set_bus_speed(struct udevice *bus, unsigned int speed) +{ + struct uniphier_i2c_dev *priv = dev_get_priv(bus); + + /* max supported frequency is 400 kHz */ + if (speed > 400000) + return -EINVAL; + + /* bus reset: make sure the bus is idle when change the frequency */ + writel(0x1, &priv->regs->brst); + + writel((priv->input_clk / speed / 2 << 16) | (priv->input_clk / speed), + &priv->regs->clk); + + writel(0x3, &priv->regs->brst); + + /* + * Theoretically, each byte can be transferred in + * 1000000 * 9 / speed usec. For safety, wait more than double. + */ + priv->wait_us = 20000000 / speed; + + return 0; +} + + +static const struct dm_i2c_ops uniphier_i2c_ops = { + .xfer = uniphier_i2c_xfer, + .set_bus_speed = uniphier_i2c_set_bus_speed, +}; + +static const struct udevice_id uniphier_i2c_of_match[] = { + { .compatible = "panasonic,uniphier-i2c" }, + {}, +}; + +U_BOOT_DRIVER(uniphier_i2c) = { + .name = "uniphier-i2c", + .id = UCLASS_I2C, + .of_match = uniphier_i2c_of_match, + .probe = uniphier_i2c_probe, + .remove = uniphier_i2c_remove, + .priv_auto_alloc_size = sizeof(struct uniphier_i2c_dev), + .ops = &uniphier_i2c_ops, +}; |