[U-Boot] [PATCH v4 2/5] i2c: UniPhier: add driver for UniPhier i2c controller
Masahiro Yamada
yamada.m at jp.panasonic.com
Tue Jan 6 06:13:43 CET 2015
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>
Reviewed-by: Simon Glass <sjg at chromium.org>
Acked-by: Heiko Schocher <hs at denx.de>
---
Changes in v4:
- Use a structure instead of macros for register access
Changes in v3: None
Changes in v2:
- Fix a typo. s/freqency/frequency/
- Add some comments to explain the formula calculating
wait time.
- add comments on every register
- skip stop condition if the next message is read
drivers/i2c/Kconfig | 8 ++
drivers/i2c/Makefile | 1 +
drivers/i2c/i2c-uniphier.c | 236 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 245 insertions(+)
create mode 100644 drivers/i2c/i2c-uniphier.c
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 96715d0..6a479ef 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -4,3 +4,11 @@ config DM_I2C
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..a041031
--- /dev/null
+++ b/drivers/i2c/i2c-uniphier.c
@@ -0,0 +1,236 @@
+/*
+ * 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 <linux/compiler.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 */
+} __packed;
+
+#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 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->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;
+
+ 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;
+
+ 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,
+ .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
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