[U-Boot] [PATCH 1/4] i2c: UniPhier: add driver for UniPhier i2c controller
Simon Glass
sjg at chromium.org
Tue Dec 23 20:54:53 CET 2014
Hi Masahiro,
On 22 December 2014 at 03:58, Masahiro Yamada <yamada.m at jp.panasonic.com> wrote:
> This commit adds on-chip I2C driver used on some old Panasonic
> UniPhier SoCs.
>
> Signed-off-by: Masahiro Yamada <yamada.m at jp.panasonic.com>
>From a driver model perspective:
Reviewed-by: Simon Glass <sjg at chromium.org>
A few comments below.
> ---
>
> drivers/i2c/Kconfig | 14 +++
> drivers/i2c/Makefile | 1 +
> drivers/i2c/i2c-uniphier.c | 225 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 240 insertions(+)
> create mode 100644 drivers/i2c/i2c-uniphier.c
>
> diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
> index e69de29..6a479ef 100644
> --- a/drivers/i2c/Kconfig
> +++ b/drivers/i2c/Kconfig
> @@ -0,0 +1,14 @@
> +config DM_I2C
> + bool "Enable Driver Model for I2C drivers"
> + depends on DM
> + help
> + If you want to use driver model for I2C drivers, say Y.
> + To use legacy I2C drivers, say N.
> +
> +config SYS_I2C_UNIPHIER
> + bool "UniPhier I2C driver"
> + depends on ARCH_UNIPHIER && DM_I2C
> + default y
> + help
> + Support for Panasonic UniPhier I2C controller driver. This I2C
> + controller is used on PH1-LD4, PH1-sLD8 or older UniPhier SoCs.
> diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
> index 6f3c86c..e2fcd24 100644
> --- a/drivers/i2c/Makefile
> +++ b/drivers/i2c/Makefile
> @@ -31,4 +31,5 @@ obj-$(CONFIG_SYS_I2C_SANDBOX) += sandbox_i2c.o i2c-emul-uclass.o
> obj-$(CONFIG_SYS_I2C_SH) += sh_i2c.o
> obj-$(CONFIG_SYS_I2C_SOFT) += soft_i2c.o
> obj-$(CONFIG_SYS_I2C_TEGRA) += tegra_i2c.o
> +obj-$(CONFIG_SYS_I2C_UNIPHIER) += i2c-uniphier.o
> obj-$(CONFIG_SYS_I2C_ZYNQ) += zynq_i2c.o
> diff --git a/drivers/i2c/i2c-uniphier.c b/drivers/i2c/i2c-uniphier.c
> new file mode 100644
> index 0000000..05035ac
> --- /dev/null
> +++ b/drivers/i2c/i2c-uniphier.c
> @@ -0,0 +1,225 @@
> +/*
> + * Copyright (C) 2014 Panasonic Corporation
> + * Author: Masahiro Yamada <yamada.m at 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;
> +
> +#define I2C_DTRM 0x00 /* 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)
> +#define I2C_DREC 0x04 /* data reception */
> +#define I2C_DREC_STS (1 << 12)
> +#define I2C_DREC_LRB (1 << 11)
> +#define I2C_DREC_LAB (1 << 9)
> +#define I2C_MYAD 0x08
> +#define I2C_CLK 0x0c
> +#define I2C_BRST 0x10 /* bus reset */
> +#define I2C_BRST_FOEN (1 << 1)
> +#define I2C_BRST_BRST (1 << 0)
> +#define I2C_HOLD 0x14
> +#define I2C_BSTS 0x18
> +#define I2C_NOISE 0x1c
> +#define I2C_SETUP 0x20
> +
> +#define IOBUS_FREQ 100000000
> +
> +struct uniphier_i2c_dev {
> + void __iomem *base; /* register base */
U-Boot normally uses a struct for register access.
> + 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->base = map_sysmem(addr, size);
> +
> + if (!priv->base)
> + return -ENOMEM;
> +
> + priv->input_clk = IOBUS_FREQ;
> +
> + /* deassert reset */
> + writel(0x3, priv->base + I2C_BRST);
> +
> + return 0;
> +}
> +
> +static int uniphier_i2c_remove(struct udevice *dev)
> +{
> + struct uniphier_i2c_dev *priv = dev_get_priv(dev);
> +
> + unmap_sysmem(priv->base);
> +
> + return 0;
> +}
> +
> +static int uniphier_i2c_child_pre_probe(struct udevice *dev)
> +{
> + struct dm_i2c_chip *i2c_chip = dev_get_parentdata(dev);
> +
> + if (dev->of_offset == -1)
> + return 0;
> + return i2c_chip_ofdata_to_platdata(gd->fdt_blob, dev->of_offset,
> + i2c_chip);
> +}
> +
> +static int send_and_recv_byte(struct uniphier_i2c_dev *dev, u32 dtrm)
> +{
> + writel(dtrm, dev->base + I2C_DTRM);
> +
> + /*
> + * U-Boot does not have a good support of interrupt.
> + * Wait for a while.
> + */
> + udelay(dev->wait_us);
It might be possible to check a 'ready' bit in the hardware, but I
suppose this works and is simple for what sounds like old hardware.
> +
> + return readl(dev->base + I2C_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)
> +{
> + int ret;
> + bool stop = true;
> +
> + 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->base + I2C_DTRM);
> +
> + return ret;
> +}
> +
> +static int uniphier_i2c_receive(struct uniphier_i2c_dev *dev,
> + uint addr, uint len, u8 *buf)
> +{
> + int ret;
> + bool stop = true;
> +
> + 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->base + I2C_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);
> +
> + for (; nmsgs > 0; nmsgs--, msg++) {
> + if (msg->flags & I2C_M_RD)
> + ret = uniphier_i2c_receive(dev, msg->addr,
> + msg->len, msg->buf);
> + else
> + ret = uniphier_i2c_transmit(dev, msg->addr,
> + msg->len, msg->buf);
> +
> + 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 freqency */
> + writel(0x1, priv->base + I2C_BRST);
> +
> + writel((priv->input_clk / speed / 2 << 16) | (priv->input_clk / speed),
> + priv->base + I2C_CLK);
> +
> + writel(0x3, priv->base + I2C_BRST);
> +
> + priv->wait_us = 20000000 / speed;
How is that calculated? Perhaps have a comment?
> +
> + 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,
> + .per_child_auto_alloc_size = sizeof(struct dm_i2c_chip),
> + .child_pre_probe = uniphier_i2c_child_pre_probe,
> + .priv_auto_alloc_size = sizeof(struct uniphier_i2c_dev),
> + .ops = &uniphier_i2c_ops,
> +};
> --
> 1.9.1
Regards,
Simon
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