[U-Boot] [PATCH 1/2] I2C: add Marvell TWSI simple driver
Albert Aribaud
albert.aribaud at free.fr
Wed Aug 25 16:23:32 CEST 2010
This driver is for the Marvell TWSI/I2C module found in
the orion and kirkwood families among others.
Signed-off-by: Albert Aribaud <albert.aribaud at free.fr>
---
While the 'kirkwood_i2c' driver for the Marvell TWSI module
is already available in u-boot, this one is 25% smaller, less
complex (no state machine) and much faster (i2c probe on an
ED Mini V2 takes no noticeable time vs. half a second).
drivers/i2c/Makefile | 1 +
drivers/i2c/mvtwsi.c | 419 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 420 insertions(+), 0 deletions(-)
create mode 100644 drivers/i2c/mvtwsi.c
diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index d2c2515..73c415d 100644
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -30,6 +30,7 @@ COBJS-$(CONFIG_DRIVER_DAVINCI_I2C) += davinci_i2c.o
COBJS-$(CONFIG_FSL_I2C) += fsl_i2c.o
COBJS-$(CONFIG_I2C_KIRKWOOD) += kirkwood_i2c.o
COBJS-$(CONFIG_I2C_MXC) += mxc_i2c.o
+COBJS-$(CONFIG_I2C_DRIVER_MVTWSI) += mvtwsi.o
COBJS-$(CONFIG_DRIVER_OMAP1510_I2C) += omap1510_i2c.o
COBJS-$(CONFIG_DRIVER_OMAP24XX_I2C) += omap24xx_i2c.o
COBJS-$(CONFIG_DRIVER_OMAP34XX_I2C) += omap24xx_i2c.o
diff --git a/drivers/i2c/mvtwsi.c b/drivers/i2c/mvtwsi.c
new file mode 100644
index 0000000..b591328
--- /dev/null
+++ b/drivers/i2c/mvtwsi.c
@@ -0,0 +1,419 @@
+/*
+ * Driver for the TWSI (i2c) controller on the Marvell orion5x
+ *
+ * Author: Albert Aribaud <albert.aribaud at free.fr>
+ * 2005 (c) MontaVista, Software, Inc.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301 USA
+ */
+
+#include <common.h>
+#include <i2c.h>
+#include <asm/errno.h>
+#include <asm/io.h>
+
+/*
+ * include a file that will provide CONFIG_I2C_MVTWSI_BASE
+ * and possibly other settings
+ */
+
+#if defined(CONFIG_ORION5X)
+#include <asm/arch/orion5x.h>
+#else
+#error Driver mvtwsi not supported by SoC or board
+#endif
+
+/*
+ * TWSI register structure
+ */
+
+struct mvtwsi_registers {
+ u32 slave_address;
+ u32 data;
+ u32 control;
+ union {
+ u32 status; /* when reading */
+ u32 baudrate; /* when writing */
+ };
+ u32 extended_slave_address;
+ u32 reserved[2];
+ u32 soft_reset;
+};
+
+/*
+ * Control register fields
+ */
+
+#define MVTWSI_CONTROL_ACK 0x00000004
+#define MVTWSI_CONTROL_IFLG 0x00000008
+#define MVTWSI_CONTROL_STOP 0x00000010
+#define MVTWSI_CONTROL_START 0x00000020
+#define MVTWSI_CONTROL_TWSIEN 0x00000040
+#define MVTWSI_CONTROL_INTEN 0x00000080
+
+/*
+ * Status register values -- only those expected in normal master
+ * operation on non-10-bit-address devices; whatever status we don't
+ * expect in nominal conditions (bus errors, arbitration losses,
+ * missing ACKs...) we just pass back to the caller as an error
+ * code.
+ */
+
+#define MVTWSI_STATUS_START 0x08
+#define MVTWSI_STATUS_REPEATED_START 0x10
+#define MVTWSI_STATUS_ADDR_W_ACK 0x18
+#define MVTWSI_STATUS_DATA_W_ACK 0x28
+#define MVTWSI_STATUS_ADDR_R_ACK 0x40
+#define MVTWSI_STATUS_ADDR_R_NAK 0x48
+#define MVTWSI_STATUS_DATA_R_ACK 0x50
+#define MVTWSI_STATUS_DATA_R_NAK 0x58 /* our NAK, not the slave's */
+#define MVTWSI_STATUS_IDLE 0xF8
+
+/*
+ * The single instance of the controller we'll be dealing with
+ */
+
+static struct mvtwsi_registers *twsi =
+ (struct mvtwsi_registers *) CONFIG_I2C_MVTWSI_BASE;
+
+/*
+ * Returned statuses are 0 for success and nonzero otherwise.
+ * Currently, cmd_i2c and cmd_eeprom do not interpret an error status.
+ * Thus to ease debugging, the return status contains some debug info:
+ * - bits 31..24 are an error class: 0x01 is timeout, 0x02 is 'status mismatch'.
+ * - bits 23..16 are the last value of the control register.
+ * - bits 15..8 are the last value of the status register.
+ * - bits 7..0 are the expected value of the status register.
+ */
+
+#define MVTWSI_ERROR_WRONG_STATUS 0x01
+#define MVTWSI_ERROR_TIMEOUT 0x02
+
+#define MVTWSI_ERROR(ec,lc,ls,es) ( ( (ec << 24) & 0xFF000000) | \
+ ( (lc << 16) & 0x00FF0000) | ( (ls<<8) & 0x0000FF00) | (es & 0xFF) )
+
+/*
+ * Wait for IFLG to raise, or return 'timeout'; then if status is as expected,
+ * return 0 (ok) or return 'wrong status'.
+ */
+
+static int twsi_wait(int expected_status)
+{
+ int control,status;
+ int timeout = 1000;
+ do {
+ control = readl(&twsi->control);
+ if (control & MVTWSI_CONTROL_IFLG) {
+ status = readl(&twsi->status);
+ if (status==expected_status)
+ return 0;
+ else
+ return MVTWSI_ERROR(MVTWSI_ERROR_WRONG_STATUS,control, status,
+ expected_status);
+ }
+ udelay(10);
+ } while (timeout--);
+ status = readl(&twsi->status);
+ return MVTWSI_ERROR(MVTWSI_ERROR_TIMEOUT,control,status,expected_status);
+}
+
+/*
+ * These flags are ORed to any write to the control register
+ * They allow global setting of TWSIEN and ACK.
+ * By default none are set.
+ * twsi_start() sets TWSIEN (in case the controller was disabled)
+ * twsi_recv() sets ACK or resets it depending on expected status.
+ */
+
+static u8 twsi_control_flags = MVTWSI_CONTROL_TWSIEN;
+
+/*
+ * Assert the START condition, either in a single I2C transaction
+ * or inside back-to-back ones (repeated starts).
+ */
+
+static int twsi_start(int expected_status)
+{
+ /* globally set TWSIEN in case it was not */
+ twsi_control_flags |= MVTWSI_CONTROL_TWSIEN;
+ /* assert START */
+ writel(twsi_control_flags | MVTWSI_CONTROL_START, &twsi->control);
+ /* wait for controller to process START */
+ return twsi_wait(expected_status);
+}
+
+/*
+ * Send a byte (i2c address or data).
+ */
+
+static int twsi_send(u8 byte, int expected_status)
+{
+ /* put byte in data register for sending */
+ writel(byte, &twsi->data);
+ /* clear any pending interrupt -- that'll cause sending */
+ writel(twsi_control_flags, &twsi->control);
+ /* wait for controller to receive byte and check ACK */
+ return twsi_wait(expected_status);
+}
+
+/*
+ * Receive a byte.
+ * Global mvtwsi_control_flags variable says if we should ack or nak.
+ */
+
+static int twsi_recv(u8 *byte)
+{
+ int expected_status, status;
+ /* compute expected status based on ACK bit in global control flags */
+ if (twsi_control_flags & MVTWSI_CONTROL_ACK)
+ expected_status = MVTWSI_STATUS_DATA_R_ACK;
+ else
+ expected_status = MVTWSI_STATUS_DATA_R_NAK;
+ /* acknowledge *previous state* and launch receive */
+ writel(twsi_control_flags, &twsi->control);
+ /* wait for controller to receive byte and assert ACK or NAK */
+ status = twsi_wait(expected_status);
+ /* if we did receive expected byte then store it */
+ if (status==0)
+ *byte = readl(&twsi->data);
+ /* return status */
+ return status;
+}
+
+/*
+ * Assert the STOP condition.
+ * This is also used to force the bus back in idle (SDA=SCL=1).
+ */
+
+static int twsi_stop(void)
+{
+ int control,status;
+ int timeout = 1000;
+ /* assert STOP */
+ control = MVTWSI_CONTROL_TWSIEN | MVTWSI_CONTROL_STOP;
+ writel(control, &twsi->control);
+ /* wait for idle condition. There won't be an IFLG so we cannot use twsi_wait(). */
+ do {
+ status = readl(&twsi->status);
+ if (status==MVTWSI_STATUS_IDLE)
+ return 0;
+ udelay(10);
+ } while (timeout--);
+ control = readl(&twsi->control);
+ return MVTWSI_ERROR(MVTWSI_ERROR_TIMEOUT,control,status,MVTWSI_STATUS_IDLE);
+}
+
+/*
+ * Ugly formula to convert m and n values to a frequency comes from
+ * TWSI specifications
+ */
+
+#define TWSI_FREQUENCY(m,n) \
+ ( (u8) (CONFIG_SYS_TCLK / (10 * (m + 1) * 2 * (1 << n))) )
+
+/*
+ * These are required to be reprogrammed before enabling the controller
+ * because a reset loses them.
+ * Default values come from the spec, but a twsi_reset will change them.
+ */
+
+static u8 twsi_baud_rate = 0x44;
+static u8 twsi_actual_speed = TWSI_FREQUENCY(4,4);
+static u8 twsi_slave_address = 0;
+
+/*
+ * Reset controller.
+ * Called at end of i2c_init unsuccessful i2c transactions.
+ * Controller reset also resets the baud rate and slave address, so
+ * re-establish them.
+ */
+
+static void twsi_reset(void)
+{
+ /* ensure controller will be enabled by any twsi*() function */
+ twsi_control_flags = MVTWSI_CONTROL_TWSIEN;
+ /* reset controller */
+ writel(0, &twsi->soft_reset);
+ /* wait 2 ms -- this is what the Marvell LSP does */
+ udelay(20000);
+ /* set baud rate */
+ writel(twsi_baud_rate, &twsi->baudrate);
+ /* set slave address even though we don't use it */
+ writel(twsi_slave_address, &twsi->slave_address);
+ writel(0, &twsi->extended_slave_address);
+ /* assert STOP but don't care for the result */
+ (void) twsi_stop();
+}
+
+/*
+ * I2C init called by cmd_i2c when doing 'i2c reset'.
+ * Sets baud to the highest possible value not exceeding requested one.
+ */
+
+void i2c_init(int requested_speed, int slaveadd)
+{
+ int tmp_speed, highest_speed, n, m;
+ int baud = 0x44; /* value at controller reset */
+ /* use actual speed to collect progressively higher values */
+ highest_speed = 0;
+ /* compute m,n setting for highest speed not above requested speed */
+ for (n = 0; n < 8; n++) {
+ for (m = 0; m < 16; m++) {
+ tmp_speed = TWSI_FREQUENCY(m,n);
+ if (tmp_speed <= requested_speed)
+ if (tmp_speed > highest_speed) {
+ highest_speed = tmp_speed;
+ baud = (m << 3) | n;
+ }
+ }
+ }
+ /* save baud rate and slave for later calls to twsi_reset */
+ twsi_baud_rate = baud;
+ twsi_actual_speed = highest_speed;
+ twsi_slave_address = slaveadd;
+ /* reset controller */
+ twsi_reset();
+}
+
+/*
+ * Begin I2C transaction with expected start status, at given address.
+ * Common to i2c_probe, i2c_read and i2c_write.
+ * Expected address status will derive from direction bit (bit 0) in addr.
+ */
+
+static int i2c_begin(int expected_start_status, u8 addr)
+{
+ int status, expected_addr_status;
+ /* compute expected address status from direction bit in addr */
+ if (addr & 1) /* reading */
+ expected_addr_status = MVTWSI_STATUS_ADDR_R_ACK;
+ else /* writing */
+ expected_addr_status = MVTWSI_STATUS_ADDR_W_ACK;
+ /* assert START */
+ status = twsi_start(expected_start_status);
+ /* send out the address if the start went well */
+ if (status == 0)
+ status = twsi_send(addr, expected_addr_status);
+ /* return ok or status of first failure to caller */
+ return status;
+}
+
+/*
+ * End I2C transaction, of which the current status is given.
+ * Common to i2c_probe, i2c_read and i2c_write.
+ */
+
+static int i2c_end(int status)
+{
+ /* if transaction went well so far, try to assert a STOP */
+ /*if (status == 0)*/
+ twsi_stop();
+ /* if anything went wrong (including the STOP we tried), do a reset */
+ /*else
+ twsi_reset();*/
+ /* return ok or status of first failure to caller */
+ return status;
+}
+
+/*
+ * I2C probe called by cmd_i2c when doing 'i2c probe'.
+ * Begin read, nak data byte, end.
+ */
+
+int i2c_probe(uchar chip)
+{
+ u8 dummy_byte;
+ int status;
+ /* begin i2c read */
+ status = i2c_begin(MVTWSI_STATUS_START, (chip << 1) | 1 );
+ /* dummy read was accepted: receive byte but NAK it. */
+ if (status==0)
+ status = twsi_recv( &dummy_byte);
+ /* We expected either 0 (ok) or MVTWSI_STATUS_ADDR_R_NAK */
+ return i2c_end( (status==MVTWSI_STATUS_ADDR_R_NAK) ? 0: status);
+}
+
+/*
+ * I2C read called by cmd_i2c when doing 'i2c read' and by cmd_eeprom.c
+ * Begin write, send address byte(s), begin read, receive data bytes, end.
+ */
+
+int i2c_read(u8 dev, uint addr, int alen, u8 *data, int length)
+{
+ int status;
+ /* begin i2c write to send the address bytes */
+ status = i2c_begin(MVTWSI_STATUS_START, (dev << 1) );
+ /* send addr bytes */
+ while ( (status==0) && alen--)
+ status = twsi_send(addr >> (8*alen), MVTWSI_STATUS_DATA_W_ACK);
+ /* NOTE: should we send a stop before a start? That's eeprom-level stuff */
+ /* begin i2c read to receive eeprom data bytes */
+ if (status == 0)
+ status = i2c_begin(MVTWSI_STATUS_REPEATED_START, (dev << 1) | 1);
+ /* prepare ACK if at least one byte must be received */
+ if (length > 0)
+ twsi_control_flags |= MVTWSI_CONTROL_ACK;
+ /* now receive actual bytes */
+ while ( (status==0) && length-- ) {
+ /* reset NAK if we if no more to read now */
+ if (length == 0)
+ twsi_control_flags &= ~MVTWSI_CONTROL_ACK;
+ /* read current byte */
+ status = twsi_recv(data++);
+ }
+ /* end i2c transaction */
+ return i2c_end(status);
+}
+
+/*
+ * I2C write called by cmd_i2c when doing 'i2c write' and by cmd_eeprom.c
+ * Begin write, send address byte(s), send data bytes, end.
+ */
+
+int i2c_write(u8 dev, uint addr, int alen, u8 *data, int length)
+{
+ int status;
+ /* begin i2c write to send the eeprom adress bytes then data bytes */
+ status = i2c_begin(MVTWSI_STATUS_START, (dev << 1) );
+ /* send addr bytes */
+ while ( (status==0) && alen--)
+ status = twsi_send(addr >> (8*alen), MVTWSI_STATUS_DATA_W_ACK);
+ /* send data bytes */
+ while ( (status==0) && (length-->0) )
+ status = twsi_send(*(data++), MVTWSI_STATUS_DATA_W_ACK);
+ /* end i2c transaction */
+ return i2c_end(status);
+}
+
+/*
+ * Bus set/get routines: we only support bus 0.
+ */
+
+int i2c_set_bus_num(unsigned int bus)
+{
+ if (bus > 0) {
+ return -1;
+ }
+ return 0;
+}
+
+unsigned int i2c_get_bus_num(void)
+{
+ return 0;
+}
--
1.7.1
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