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