393 строки
8.5 KiB
C
393 строки
8.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* i2c-au1550.c: SMBus (i2c) adapter for Alchemy PSC interface
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* Copyright (C) 2004 Embedded Edge, LLC <dan@embeddededge.com>
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*
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* 2.6 port by Matt Porter <mporter@kernel.crashing.org>
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*
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* The documentation describes this as an SMBus controller, but it doesn't
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* understand any of the SMBus protocol in hardware. It's really an I2C
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* controller that could emulate most of the SMBus in software.
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*
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* This is just a skeleton adapter to use with the Au1550 PSC
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* algorithm. It was developed for the Pb1550, but will work with
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* any Au1550 board that has a similar PSC configuration.
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*/
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#include <linux/delay.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/errno.h>
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#include <linux/i2c.h>
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#include <linux/slab.h>
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#include <asm/mach-au1x00/au1000.h>
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#include <asm/mach-au1x00/au1xxx_psc.h>
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#define PSC_SEL 0x00
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#define PSC_CTRL 0x04
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#define PSC_SMBCFG 0x08
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#define PSC_SMBMSK 0x0C
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#define PSC_SMBPCR 0x10
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#define PSC_SMBSTAT 0x14
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#define PSC_SMBEVNT 0x18
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#define PSC_SMBTXRX 0x1C
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#define PSC_SMBTMR 0x20
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struct i2c_au1550_data {
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void __iomem *psc_base;
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int xfer_timeout;
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struct i2c_adapter adap;
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};
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static inline void WR(struct i2c_au1550_data *a, int r, unsigned long v)
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{
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__raw_writel(v, a->psc_base + r);
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wmb();
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}
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static inline unsigned long RD(struct i2c_au1550_data *a, int r)
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{
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return __raw_readl(a->psc_base + r);
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}
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static int wait_xfer_done(struct i2c_au1550_data *adap)
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{
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int i;
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/* Wait for Tx Buffer Empty */
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for (i = 0; i < adap->xfer_timeout; i++) {
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if (RD(adap, PSC_SMBSTAT) & PSC_SMBSTAT_TE)
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return 0;
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udelay(1);
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}
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return -ETIMEDOUT;
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}
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static int wait_ack(struct i2c_au1550_data *adap)
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{
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unsigned long stat;
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if (wait_xfer_done(adap))
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return -ETIMEDOUT;
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stat = RD(adap, PSC_SMBEVNT);
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if ((stat & (PSC_SMBEVNT_DN | PSC_SMBEVNT_AN | PSC_SMBEVNT_AL)) != 0)
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return -ETIMEDOUT;
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return 0;
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}
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static int wait_master_done(struct i2c_au1550_data *adap)
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{
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int i;
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/* Wait for Master Done. */
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for (i = 0; i < 2 * adap->xfer_timeout; i++) {
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if ((RD(adap, PSC_SMBEVNT) & PSC_SMBEVNT_MD) != 0)
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return 0;
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udelay(1);
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}
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return -ETIMEDOUT;
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}
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static int
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do_address(struct i2c_au1550_data *adap, unsigned int addr, int rd, int q)
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{
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unsigned long stat;
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/* Reset the FIFOs, clear events. */
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stat = RD(adap, PSC_SMBSTAT);
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WR(adap, PSC_SMBEVNT, PSC_SMBEVNT_ALLCLR);
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if (!(stat & PSC_SMBSTAT_TE) || !(stat & PSC_SMBSTAT_RE)) {
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WR(adap, PSC_SMBPCR, PSC_SMBPCR_DC);
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while ((RD(adap, PSC_SMBPCR) & PSC_SMBPCR_DC) != 0)
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cpu_relax();
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udelay(50);
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}
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/* Write out the i2c chip address and specify operation */
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addr <<= 1;
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if (rd)
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addr |= 1;
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/* zero-byte xfers stop immediately */
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if (q)
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addr |= PSC_SMBTXRX_STP;
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/* Put byte into fifo, start up master. */
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WR(adap, PSC_SMBTXRX, addr);
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WR(adap, PSC_SMBPCR, PSC_SMBPCR_MS);
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if (wait_ack(adap))
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return -EIO;
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return (q) ? wait_master_done(adap) : 0;
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}
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static int wait_for_rx_byte(struct i2c_au1550_data *adap, unsigned char *out)
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{
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int j;
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if (wait_xfer_done(adap))
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return -EIO;
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j = adap->xfer_timeout * 100;
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do {
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j--;
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if (j <= 0)
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return -EIO;
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if ((RD(adap, PSC_SMBSTAT) & PSC_SMBSTAT_RE) == 0)
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j = 0;
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else
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udelay(1);
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} while (j > 0);
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*out = RD(adap, PSC_SMBTXRX);
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return 0;
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}
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static int i2c_read(struct i2c_au1550_data *adap, unsigned char *buf,
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unsigned int len)
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{
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int i;
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if (len == 0)
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return 0;
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/* A read is performed by stuffing the transmit fifo with
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* zero bytes for timing, waiting for bytes to appear in the
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* receive fifo, then reading the bytes.
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*/
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i = 0;
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while (i < (len - 1)) {
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WR(adap, PSC_SMBTXRX, 0);
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if (wait_for_rx_byte(adap, &buf[i]))
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return -EIO;
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i++;
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}
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/* The last byte has to indicate transfer done. */
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WR(adap, PSC_SMBTXRX, PSC_SMBTXRX_STP);
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if (wait_master_done(adap))
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return -EIO;
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buf[i] = (unsigned char)(RD(adap, PSC_SMBTXRX) & 0xff);
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return 0;
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}
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static int i2c_write(struct i2c_au1550_data *adap, unsigned char *buf,
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unsigned int len)
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{
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int i;
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unsigned long data;
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if (len == 0)
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return 0;
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i = 0;
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while (i < (len-1)) {
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data = buf[i];
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WR(adap, PSC_SMBTXRX, data);
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if (wait_ack(adap))
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return -EIO;
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i++;
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}
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/* The last byte has to indicate transfer done. */
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data = buf[i];
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data |= PSC_SMBTXRX_STP;
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WR(adap, PSC_SMBTXRX, data);
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if (wait_master_done(adap))
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return -EIO;
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return 0;
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}
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static int
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au1550_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, int num)
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{
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struct i2c_au1550_data *adap = i2c_adap->algo_data;
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struct i2c_msg *p;
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int i, err = 0;
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WR(adap, PSC_CTRL, PSC_CTRL_ENABLE);
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for (i = 0; !err && i < num; i++) {
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p = &msgs[i];
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err = do_address(adap, p->addr, p->flags & I2C_M_RD,
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(p->len == 0));
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if (err || !p->len)
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continue;
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if (p->flags & I2C_M_RD)
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err = i2c_read(adap, p->buf, p->len);
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else
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err = i2c_write(adap, p->buf, p->len);
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}
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/* Return the number of messages processed, or the error code.
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*/
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if (err == 0)
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err = num;
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WR(adap, PSC_CTRL, PSC_CTRL_SUSPEND);
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return err;
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}
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static u32 au1550_func(struct i2c_adapter *adap)
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{
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return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
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}
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static const struct i2c_algorithm au1550_algo = {
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.master_xfer = au1550_xfer,
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.functionality = au1550_func,
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};
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static void i2c_au1550_setup(struct i2c_au1550_data *priv)
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{
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unsigned long cfg;
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WR(priv, PSC_CTRL, PSC_CTRL_DISABLE);
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WR(priv, PSC_SEL, PSC_SEL_PS_SMBUSMODE);
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WR(priv, PSC_SMBCFG, 0);
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WR(priv, PSC_CTRL, PSC_CTRL_ENABLE);
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while ((RD(priv, PSC_SMBSTAT) & PSC_SMBSTAT_SR) == 0)
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cpu_relax();
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cfg = PSC_SMBCFG_RT_FIFO8 | PSC_SMBCFG_TT_FIFO8 | PSC_SMBCFG_DD_DISABLE;
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WR(priv, PSC_SMBCFG, cfg);
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/* Divide by 8 to get a 6.25 MHz clock. The later protocol
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* timings are based on this clock.
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*/
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cfg |= PSC_SMBCFG_SET_DIV(PSC_SMBCFG_DIV8);
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WR(priv, PSC_SMBCFG, cfg);
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WR(priv, PSC_SMBMSK, PSC_SMBMSK_ALLMASK);
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/* Set the protocol timer values. See Table 71 in the
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* Au1550 Data Book for standard timing values.
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*/
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WR(priv, PSC_SMBTMR, PSC_SMBTMR_SET_TH(0) | PSC_SMBTMR_SET_PS(20) | \
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PSC_SMBTMR_SET_PU(20) | PSC_SMBTMR_SET_SH(20) | \
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PSC_SMBTMR_SET_SU(20) | PSC_SMBTMR_SET_CL(20) | \
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PSC_SMBTMR_SET_CH(20));
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cfg |= PSC_SMBCFG_DE_ENABLE;
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WR(priv, PSC_SMBCFG, cfg);
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while ((RD(priv, PSC_SMBSTAT) & PSC_SMBSTAT_SR) == 0)
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cpu_relax();
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WR(priv, PSC_CTRL, PSC_CTRL_SUSPEND);
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}
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static void i2c_au1550_disable(struct i2c_au1550_data *priv)
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{
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WR(priv, PSC_SMBCFG, 0);
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WR(priv, PSC_CTRL, PSC_CTRL_DISABLE);
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}
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/*
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* registering functions to load algorithms at runtime
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* Prior to calling us, the 50MHz clock frequency and routing
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* must have been set up for the PSC indicated by the adapter.
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*/
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static int
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i2c_au1550_probe(struct platform_device *pdev)
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{
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struct i2c_au1550_data *priv;
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struct resource *r;
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int ret;
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priv = devm_kzalloc(&pdev->dev, sizeof(struct i2c_au1550_data),
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GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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priv->psc_base = devm_ioremap_resource(&pdev->dev, r);
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if (IS_ERR(priv->psc_base))
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return PTR_ERR(priv->psc_base);
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priv->xfer_timeout = 200;
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priv->adap.nr = pdev->id;
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priv->adap.algo = &au1550_algo;
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priv->adap.algo_data = priv;
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priv->adap.dev.parent = &pdev->dev;
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strscpy(priv->adap.name, "Au1xxx PSC I2C", sizeof(priv->adap.name));
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/* Now, set up the PSC for SMBus PIO mode. */
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i2c_au1550_setup(priv);
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ret = i2c_add_numbered_adapter(&priv->adap);
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if (ret) {
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i2c_au1550_disable(priv);
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return ret;
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}
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platform_set_drvdata(pdev, priv);
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return 0;
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}
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static int i2c_au1550_remove(struct platform_device *pdev)
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{
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struct i2c_au1550_data *priv = platform_get_drvdata(pdev);
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i2c_del_adapter(&priv->adap);
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i2c_au1550_disable(priv);
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return 0;
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}
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#ifdef CONFIG_PM
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static int i2c_au1550_suspend(struct device *dev)
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{
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struct i2c_au1550_data *priv = dev_get_drvdata(dev);
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i2c_au1550_disable(priv);
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return 0;
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}
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static int i2c_au1550_resume(struct device *dev)
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{
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struct i2c_au1550_data *priv = dev_get_drvdata(dev);
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i2c_au1550_setup(priv);
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return 0;
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}
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static const struct dev_pm_ops i2c_au1550_pmops = {
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.suspend = i2c_au1550_suspend,
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.resume = i2c_au1550_resume,
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};
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#define AU1XPSC_SMBUS_PMOPS (&i2c_au1550_pmops)
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#else
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#define AU1XPSC_SMBUS_PMOPS NULL
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#endif
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static struct platform_driver au1xpsc_smbus_driver = {
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.driver = {
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.name = "au1xpsc_smbus",
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.pm = AU1XPSC_SMBUS_PMOPS,
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},
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.probe = i2c_au1550_probe,
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.remove = i2c_au1550_remove,
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};
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module_platform_driver(au1xpsc_smbus_driver);
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MODULE_AUTHOR("Dan Malek, Embedded Edge, LLC.");
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MODULE_DESCRIPTION("SMBus adapter Alchemy pb1550");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:au1xpsc_smbus");
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