--- /dev/null
+/*
+ * Freescale i.MX28 I2C Driver
+ *
+ * Copyright (C) 2011 Marek Vasut <marek.vasut@gmail.com>
+ * on behalf of DENX Software Engineering GmbH
+ *
+ * Partly based on Linux kernel i2c-mxs.c driver:
+ * Copyright (C) 2011 Wolfram Sang, Pengutronix e.K.
+ *
+ * Which was based on a (non-working) driver which was:
+ * Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved.
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <malloc.h>
+#include <i2c.h>
+#include <asm/errno.h>
+#include <asm/io.h>
+#include <asm/arch/clock.h>
+#include <asm/arch/imx-regs.h>
+#include <asm/arch/sys_proto.h>
+
+#define MXS_I2C_MAX_TIMEOUT 1000000
+
+static void mxs_i2c_reset(void)
+{
+ struct mxs_i2c_regs *i2c_regs = (struct mxs_i2c_regs *)MXS_I2C0_BASE;
+ int ret;
+ int speed = i2c_get_bus_speed();
+
+ ret = mxs_reset_block(&i2c_regs->hw_i2c_ctrl0_reg);
+ if (ret) {
+ debug("MXS I2C: Block reset timeout\n");
+ return;
+ }
+
+ writel(I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ | I2C_CTRL1_NO_SLAVE_ACK_IRQ |
+ I2C_CTRL1_EARLY_TERM_IRQ | I2C_CTRL1_MASTER_LOSS_IRQ |
+ I2C_CTRL1_SLAVE_STOP_IRQ | I2C_CTRL1_SLAVE_IRQ,
+ &i2c_regs->hw_i2c_ctrl1_clr);
+
+ writel(I2C_QUEUECTRL_PIO_QUEUE_MODE, &i2c_regs->hw_i2c_queuectrl_set);
+
+ i2c_set_bus_speed(speed);
+}
+
+static void mxs_i2c_setup_read(uint8_t chip, int len)
+{
+ struct mxs_i2c_regs *i2c_regs = (struct mxs_i2c_regs *)MXS_I2C0_BASE;
+
+ writel(I2C_QUEUECMD_RETAIN_CLOCK | I2C_QUEUECMD_PRE_SEND_START |
+ I2C_QUEUECMD_MASTER_MODE | I2C_QUEUECMD_DIRECTION |
+ (1 << I2C_QUEUECMD_XFER_COUNT_OFFSET),
+ &i2c_regs->hw_i2c_queuecmd);
+
+ writel((chip << 1) | 1, &i2c_regs->hw_i2c_data);
+
+ writel(I2C_QUEUECMD_SEND_NAK_ON_LAST | I2C_QUEUECMD_MASTER_MODE |
+ (len << I2C_QUEUECMD_XFER_COUNT_OFFSET) |
+ I2C_QUEUECMD_POST_SEND_STOP, &i2c_regs->hw_i2c_queuecmd);
+
+ writel(I2C_QUEUECTRL_QUEUE_RUN, &i2c_regs->hw_i2c_queuectrl_set);
+}
+
+static int mxs_i2c_write(uchar chip, uint addr, int alen,
+ uchar *buf, int blen, int stop)
+{
+ struct mxs_i2c_regs *i2c_regs = (struct mxs_i2c_regs *)MXS_I2C0_BASE;
+ uint32_t data, tmp;
+ int i, remain, off;
+ int timeout = MXS_I2C_MAX_TIMEOUT;
+
+ if ((alen > 4) || (alen == 0)) {
+ debug("MXS I2C: Invalid address length\n");
+ return -EINVAL;
+ }
+
+ if (stop)
+ stop = I2C_QUEUECMD_POST_SEND_STOP;
+
+ writel(I2C_QUEUECMD_PRE_SEND_START |
+ I2C_QUEUECMD_MASTER_MODE | I2C_QUEUECMD_DIRECTION |
+ ((blen + alen + 1) << I2C_QUEUECMD_XFER_COUNT_OFFSET) | stop,
+ &i2c_regs->hw_i2c_queuecmd);
+
+ data = (chip << 1) << 24;
+
+ for (i = 0; i < alen; i++) {
+ data >>= 8;
+ data |= ((char *)&addr)[alen - i - 1] << 24;
+ if ((i & 3) == 2)
+ writel(data, &i2c_regs->hw_i2c_data);
+ }
+
+ off = i;
+ for (; i < off + blen; i++) {
+ data >>= 8;
+ data |= buf[i - off] << 24;
+ if ((i & 3) == 2)
+ writel(data, &i2c_regs->hw_i2c_data);
+ }
+
+ remain = 24 - ((i & 3) * 8);
+ if (remain)
+ writel(data >> remain, &i2c_regs->hw_i2c_data);
+
+ writel(I2C_QUEUECTRL_QUEUE_RUN, &i2c_regs->hw_i2c_queuectrl_set);
+
+ while (--timeout) {
+ tmp = readl(&i2c_regs->hw_i2c_queuestat);
+ if (tmp & I2C_QUEUESTAT_WR_QUEUE_EMPTY)
+ break;
+ }
+
+ if (!timeout) {
+ debug("MXS I2C: Failed transmitting data!\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int mxs_i2c_wait_for_ack(void)
+{
+ struct mxs_i2c_regs *i2c_regs = (struct mxs_i2c_regs *)MXS_I2C0_BASE;
+ uint32_t tmp;
+ int timeout = MXS_I2C_MAX_TIMEOUT;
+
+ for (;;) {
+ tmp = readl(&i2c_regs->hw_i2c_ctrl1);
+ if (tmp & I2C_CTRL1_NO_SLAVE_ACK_IRQ) {
+ debug("MXS I2C: No slave ACK\n");
+ goto err;
+ }
+
+ if (tmp & (
+ I2C_CTRL1_EARLY_TERM_IRQ | I2C_CTRL1_MASTER_LOSS_IRQ |
+ I2C_CTRL1_SLAVE_STOP_IRQ | I2C_CTRL1_SLAVE_IRQ)) {
+ debug("MXS I2C: Error (CTRL1 = %08x)\n", tmp);
+ goto err;
+ }
+
+ if (tmp & I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ)
+ break;
+
+ if (!timeout--) {
+ debug("MXS I2C: Operation timed out\n");
+ goto err;
+ }
+
+ udelay(1);
+ }
+
+ return 0;
+
+err:
+ mxs_i2c_reset();
+ return 1;
+}
+
+int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
+{
+ struct mxs_i2c_regs *i2c_regs = (struct mxs_i2c_regs *)MXS_I2C0_BASE;
+ uint32_t tmp = 0;
+ int timeout = MXS_I2C_MAX_TIMEOUT;
+ int ret;
+ int i;
+
+ ret = mxs_i2c_write(chip, addr, alen, NULL, 0, 0);
+ if (ret) {
+ debug("MXS I2C: Failed writing address\n");
+ return ret;
+ }
+
+ ret = mxs_i2c_wait_for_ack();
+ if (ret) {
+ debug("MXS I2C: Failed writing address\n");
+ return ret;
+ }
+
+ mxs_i2c_setup_read(chip, len);
+ ret = mxs_i2c_wait_for_ack();
+ if (ret) {
+ debug("MXS I2C: Failed reading address\n");
+ return ret;
+ }
+
+ for (i = 0; i < len; i++) {
+ if (!(i & 3)) {
+ while (--timeout) {
+ tmp = readl(&i2c_regs->hw_i2c_queuestat);
+ if (!(tmp & I2C_QUEUESTAT_RD_QUEUE_EMPTY))
+ break;
+ }
+
+ if (!timeout) {
+ debug("MXS I2C: Failed receiving data!\n");
+ return -ETIMEDOUT;
+ }
+
+ tmp = readl(&i2c_regs->hw_i2c_queuedata);
+ }
+ buffer[i] = tmp & 0xff;
+ tmp >>= 8;
+ }
+
+ return 0;
+}
+
+int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
+{
+ int ret;
+ ret = mxs_i2c_write(chip, addr, alen, buffer, len, 1);
+ if (ret) {
+ debug("MXS I2C: Failed writing address\n");
+ return ret;
+ }
+
+ ret = mxs_i2c_wait_for_ack();
+ if (ret)
+ debug("MXS I2C: Failed writing address\n");
+
+ return ret;
+}
+
+int i2c_probe(uchar chip)
+{
+ int ret;
+ ret = mxs_i2c_write(chip, 0, 1, NULL, 0, 1);
+ if (!ret)
+ ret = mxs_i2c_wait_for_ack();
+ mxs_i2c_reset();
+ return ret;
+}
+
+int i2c_set_bus_speed(unsigned int speed)
+{
+ struct mxs_i2c_regs *i2c_regs = (struct mxs_i2c_regs *)MXS_I2C0_BASE;
+ /*
+ * The timing derivation algorithm. There is no documentation for this
+ * algorithm available, it was derived by using the scope and fiddling
+ * with constants until the result observed on the scope was good enough
+ * for 20kHz, 50kHz, 100kHz, 200kHz, 300kHz and 400kHz. It should be
+ * possible to assume the algorithm works for other frequencies as well.
+ *
+ * Note it was necessary to cap the frequency on both ends as it's not
+ * possible to configure completely arbitrary frequency for the I2C bus
+ * clock.
+ */
+ uint32_t clk = mxc_get_clock(MXC_XTAL_CLK);
+ uint32_t base = ((clk / speed) - 38) / 2;
+ uint16_t high_count = base + 3;
+ uint16_t low_count = base - 3;
+ uint16_t rcv_count = (high_count * 3) / 4;
+ uint16_t xmit_count = low_count / 4;
+
+ if (speed > 540000) {
+ printf("MXS I2C: Speed too high (%d Hz)\n", speed);
+ return -EINVAL;
+ }
+
+ if (speed < 12000) {
+ printf("MXS I2C: Speed too low (%d Hz)\n", speed);
+ return -EINVAL;
+ }
+
+ writel((high_count << 16) | rcv_count, &i2c_regs->hw_i2c_timing0);
+ writel((low_count << 16) | xmit_count, &i2c_regs->hw_i2c_timing1);
+
+ writel((0x0030 << I2C_TIMING2_BUS_FREE_OFFSET) |
+ (0x0030 << I2C_TIMING2_LEADIN_COUNT_OFFSET),
+ &i2c_regs->hw_i2c_timing2);
+
+ return 0;
+}
+
+unsigned int i2c_get_bus_speed(void)
+{
+ struct mxs_i2c_regs *i2c_regs = (struct mxs_i2c_regs *)MXS_I2C0_BASE;
+ uint32_t clk = mxc_get_clock(MXC_XTAL_CLK);
+ uint32_t timing0;
+
+ timing0 = readl(&i2c_regs->hw_i2c_timing0);
+ /*
+ * This is a reverse version of the algorithm presented in
+ * i2c_set_bus_speed(). Please refer there for details.
+ */
+ return clk / ((((timing0 >> 16) - 3) * 2) + 38);
+}
+
+void i2c_init(int speed, int slaveadd)
+{
+ mxs_i2c_reset();
+ i2c_set_bus_speed(speed);
+
+ return;
+}
Code Review / kvmfornfv.git / blobdiff