[1/2] i2c: keba: Add KEBA I2C controller support

Message ID	20240601192846.68146-2-gerhard@engleder-embedded.com
State	Changes Requested
Delegated to:	Andi Shyti
Headers	show Return-Path: <linux-i2c+bounces-3739-incoming=patchwork.ozlabs.org@vger.kernel.org> From: Gerhard Engleder <gerhard@engleder-embedded.com> To: linux-i2c@vger.kernel.org Cc: andi.shyti@kernel.org, arnd@arndb.de, gregkh@linuxfoundation.org, Gerhard Engleder <gerhard@engleder-embedded.com>, Gerhard Engleder <eg@keba.com> Subject: [PATCH 1/2] i2c: keba: Add KEBA I2C controller support Date: Sat, 1 Jun 2024 21:28:45 +0200 Message-Id: <20240601192846.68146-2-gerhard@engleder-embedded.com> In-Reply-To: <20240601192846.68146-1-gerhard@engleder-embedded.com> References: <20240601192846.68146-1-gerhard@engleder-embedded.com> Precedence: bulk MIME-Version: 1.0 Content-Transfer-Encoding: 8bit
Series	I2C controller support for KEBA PLCs \| expand [0/2] I2C controller support for KEBA PLCs [1/2] i2c: keba: Add KEBA I2C controller support [2/2] misc: keba: Add basic KEBA CP500 system FPGA support

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig index fe6e8a1bb607..be2611a33503 100644 --- a/drivers/i2c/busses/Kconfig +++ b/drivers/i2c/busses/Kconfig @@ -770,6 +770,16 @@ config I2C_JZ4780 If you don't know what to do here, say N. +config I2C_KEBA + tristate "KEBA I2C controller support" + depends on HAS_IOMEM + help + This driver supports the I2C controller found in KEBA system FPGA + devices. + + This driver can also be built as a module. If so, the module + will be called i2c-keba. + config I2C_KEMPLD tristate "Kontron COM I2C Controller" depends on MFD_KEMPLD diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile index 3d65934f5eb4..6c3dfa7936c7 100644 --- a/drivers/i2c/busses/Makefile +++ b/drivers/i2c/busses/Makefile @@ -77,6 +77,7 @@ obj-$(CONFIG_I2C_IMX) += i2c-imx.o obj-$(CONFIG_I2C_IMX_LPI2C) += i2c-imx-lpi2c.o obj-$(CONFIG_I2C_IOP3XX) += i2c-iop3xx.o obj-$(CONFIG_I2C_JZ4780) += i2c-jz4780.o +obj-$(CONFIG_I2C_KEBA) += i2c-keba.o obj-$(CONFIG_I2C_KEMPLD) += i2c-kempld.o obj-$(CONFIG_I2C_LPC2K) += i2c-lpc2k.o obj-$(CONFIG_I2C_LS2X) += i2c-ls2x.o diff --git a/drivers/i2c/busses/i2c-keba.c b/drivers/i2c/busses/i2c-keba.c new file mode 100644 index 000000000000..5f76f0ddeccf --- /dev/null +++ b/drivers/i2c/busses/i2c-keba.c @@ -0,0 +1,585 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) KEBA AG 2012 + * Copyright (C) KEBA Industrial Automation Gmbh 2024 + * + * Driver for KEBA I2C controller FPGA IP core + */ + +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/io.h> +#include <linux/iopoll.h> +#include <linux/i2c.h> +#include <linux/platform_data/i2c-keba.h> + +#define KI2C "i2c-keba" + +#define KI2C_CAPABILITY_REG 0x02 +#define KI2C_CONTROL_REG 0x04 +#define KI2C_CONTROL_DC_REG 0x05 +#define KI2C_STATUS_REG 0x08 +#define KI2C_STATUS_DC_REG 0x09 +#define KI2C_DATA_REG 0x0c + +#define KI2C_CAPABILITY_CRYPTO 0x01 +#define KI2C_CAPABILITY_DC 0x02 + +#define KI2C_CONTROL_MEN 0x01 +#define KI2C_CONTROL_MSTA 0x02 +#define KI2C_CONTROL_RSTA 0x04 +#define KI2C_CONTROL_MTX 0x08 +#define KI2C_CONTROL_TXAK 0x10 + +#define KI2C_STATUS_IN_USE 0x01 +#define KI2C_STATUS_ACK_CYC 0x02 +#define KI2C_STATUS_RXAK 0x04 +#define KI2C_STATUS_MCF 0x08 + +#define KI2C_DC_SDA 0x01 +#define KI2C_DC_SCL 0x02 + +#define KI2C_INUSE_SLEEP_US (2 * USEC_PER_MSEC) +#define KI2C_INUSE_TIMEOUT_US (10 * USEC_PER_SEC) + +#define KI2C_POLL_DELAY_US 5 + +struct ki2c { + struct platform_device *pdev; + void __iomem *base; + struct i2c_adapter adapter; + + struct i2c_client **client; + int client_size; +}; + +static int ki2c_inuse_lock(struct ki2c *ki2c) +{ + u8 sts; + int ret; + + /* The I2C controller has an IN_USE bit for locking access to the + * controller. This enables the use of I2C controller by other none + * Linux processors. + * + * If the I2C controller is free, then the first read returns + * IN_USE == 0. After that the I2C controller is locked and further + * reads of IN_USE return 1. + * + * The I2C controller is unlocked by writing 1 into IN_USE. + */ + ret = readb_poll_timeout(ki2c->base + KI2C_STATUS_REG, + sts, (sts & KI2C_STATUS_IN_USE) == 0, + KI2C_INUSE_SLEEP_US, KI2C_INUSE_TIMEOUT_US); + if (ret != 0) + dev_warn(&ki2c->pdev->dev, "%s err!\n", __func__); + + return ret; +} + +static void ki2c_inuse_unlock(struct ki2c *ki2c) +{ + /* unlock the controller by writing 1 into IN_USE */ + iowrite8(KI2C_STATUS_IN_USE, ki2c->base + KI2C_STATUS_REG); +} + +static int ki2c_wait_for_bit(u8 mask, void __iomem *addr, unsigned long timeout) +{ + u8 val; + + return readb_poll_timeout(addr, val, (val & mask), KI2C_POLL_DELAY_US, + jiffies_to_usecs(timeout)); +} + +static int ki2c_wait_for_mcf(struct ki2c *ki2c) +{ + return ki2c_wait_for_bit(KI2C_STATUS_MCF, ki2c->base + KI2C_STATUS_REG, + ki2c->adapter.timeout); +} + +static int ki2c_wait_for_data(struct ki2c *ki2c) +{ + int ret; + + ret = ki2c_wait_for_mcf(ki2c); + if (ret < 0) + return ret; + + return ki2c_wait_for_bit(KI2C_STATUS_ACK_CYC, + ki2c->base + KI2C_STATUS_REG, + ki2c->adapter.timeout); +} + +static int ki2c_wait_for_data_ack(struct ki2c *ki2c) +{ + int ret; + + ret = ki2c_wait_for_data(ki2c); + if (ret < 0) + return ret; + + /* RXAK == 0 means ACK reveived */ + if (ioread8(ki2c->base + KI2C_STATUS_REG) & KI2C_STATUS_RXAK) + return -EIO; + + return 0; +} + +static int ki2c_has_capability(struct ki2c *ki2c, unsigned int cap) +{ + return (ioread8(ki2c->base + KI2C_CAPABILITY_REG) & cap) != 0; +} + +static int ki2c_get_scl(struct ki2c *ki2c) +{ + /* capability KI2C_CAPABILITY_DC required */ + return (ioread8(ki2c->base + KI2C_STATUS_DC_REG) & KI2C_DC_SCL) != 0; +} + +static int ki2c_get_sda(struct ki2c *ki2c) +{ + /* capability KI2C_CAPABILITY_DC required */ + return (ioread8(ki2c->base + KI2C_STATUS_DC_REG) & KI2C_DC_SDA) != 0; +} + +static void ki2c_set_scl(struct ki2c *ki2c, int val) +{ + u8 control_dc; + + /* capability KI2C_CAPABILITY_DC and KI2C_CONTROL_MEN = 0 reqired */ + control_dc = ioread8(ki2c->base + KI2C_CONTROL_DC_REG); + if (val) + control_dc |= KI2C_DC_SCL; + else + control_dc &= ~KI2C_DC_SCL; + iowrite8(control_dc, ki2c->base + KI2C_CONTROL_DC_REG); +} + +/* + * Resetting bus bitwise is done by checking SDA and applying clock cycles as + * long as SDA is low. 9 clock cycles are applied at most. + * + * Clock cycles are generated and ndelay() determines the duration of clock + * cycles. Generated clock rate is 100 KHz and so duration of both clock levels + * is: delay in ns = (10^6 / 100) / 2 + */ +#define KI2C_RECOVERY_CLK_CNT 9 +#define KI2C_RECOVERY_NDELAY 5000 +static int ki2c_reset_bus_bitwise(struct ki2c *ki2c) +{ + int count = 0; + int val = 1; + int ret = 0; + + /* disable I2C controller (MEN = 0) to get direct access to SCL/SDA */ + iowrite8(0, ki2c->base + KI2C_CONTROL_REG); + + /* generate clock cycles */ + ki2c_set_scl(ki2c, val); + ndelay(KI2C_RECOVERY_NDELAY); + while (count++ < KI2C_RECOVERY_CLK_CNT * 2) { + if (val) { + /* SCL shouldn't be low here */ + if (!ki2c_get_scl(ki2c)) { + dev_err(&ki2c->pdev->dev, + "SCL is stuck low!\n"); + ret = -EBUSY; + break; + } + + /* break if SDA is high */ + if (ki2c_get_sda(ki2c)) + break; + } + + val = !val; + ki2c_set_scl(ki2c, val); + ndelay(KI2C_RECOVERY_NDELAY); + } + + if (!ki2c_get_sda(ki2c)) { + dev_err(&ki2c->pdev->dev, "SDA is still low!\n"); + ret = -EBUSY; + } + + /* reenable controller */ + iowrite8(KI2C_CONTROL_MEN, ki2c->base + KI2C_CONTROL_REG); + + return ret; +} + +/* + * Resetting bus bytewise is done by writing start bit, 9 data bits and stop + * bit. + * + * This is not 100% safe. If slave is an EEPROM and a write access was + * interrupted during the ACK cycle, this approach might not be able to recover + * the bus. The reason is, that after the 9 clock cycles the EEPROM will be in + * ACK cycle again and will hold SDA low like it did before the start of the + * routine. Furthermore the EEPROM might get written one additional byte with + * 0xff into it. Thus, use bitwise approach whenever possible, especially when + * EEPROMs are on the bus. + */ +static int ki2c_reset_bus_bytewise(struct ki2c *ki2c) +{ + int ret; + + /* hold data line high for 9 clock cycles */ + iowrite8(0xFF, ki2c->base + KI2C_DATA_REG); + + /* create start condition */ + iowrite8(KI2C_CONTROL_MEN | KI2C_CONTROL_MTX | KI2C_CONTROL_MSTA | KI2C_CONTROL_TXAK, + ki2c->base + KI2C_CONTROL_REG); + ret = ki2c_wait_for_mcf(ki2c); + if (ret < 0) + return ret; + + /* create stop condition */ + iowrite8(KI2C_CONTROL_MEN | KI2C_CONTROL_MTX | KI2C_CONTROL_TXAK, + ki2c->base + KI2C_CONTROL_REG); + ret = ki2c_wait_for_mcf(ki2c); + + return ret; +} + +static int ki2c_reset_bus(struct ki2c *ki2c) +{ + int ret; + + ret = ki2c_inuse_lock(ki2c); + if (ret < 0) + return ret; + + /* If the I2C controller is capable of direct control of SCL/SDA, then a + * bitwise reset is used. Otherwise fall back to bytewise reset. + */ + if (ki2c_has_capability(ki2c, KI2C_CAPABILITY_DC)) + ret = ki2c_reset_bus_bitwise(ki2c); + else + ret = ki2c_reset_bus_bytewise(ki2c); + + ki2c_inuse_unlock(ki2c); + + return ret; +} + +static void ki2c_write_target_addr(struct ki2c *ki2c, struct i2c_msg *m) +{ + u8 addr; + + addr = m->addr << 1; + /* Bit 0 signals RD/WR */ + if (m->flags & I2C_M_RD) + addr |= 0x01; + + iowrite8(addr, ki2c->base + KI2C_DATA_REG); +} + +static int ki2c_start_addr(struct ki2c *ki2c, struct i2c_msg *m) +{ + int ret; + + /* Store target address byte in the controller. This has to be done + * before sending START condition. + */ + ki2c_write_target_addr(ki2c, m); + + /* enable controller for TX */ + iowrite8(KI2C_CONTROL_MEN | KI2C_CONTROL_MTX, + ki2c->base + KI2C_CONTROL_REG); + + /* send START condition and target address byte */ + iowrite8(KI2C_CONTROL_MEN | KI2C_CONTROL_MTX | KI2C_CONTROL_MSTA, + ki2c->base + KI2C_CONTROL_REG); + + ret = ki2c_wait_for_data_ack(ki2c); + if (ret < 0) + /* For EEPROMs this is normal behavior during internal write + * operation. + */ + dev_dbg(&ki2c->pdev->dev, "%s wait for ACK err at 0x%02x!\n", + __func__, m->addr); + + return ret; +} + +static int ki2c_repstart_addr(struct ki2c *ki2c, struct i2c_msg *m) +{ + int ret; + + /* repeated start and write is not supported */ + if ((m->flags & I2C_M_RD) == 0) { + dev_warn(&ki2c->pdev->dev, + "Repeated start not supported for writes\n"); + return -EINVAL; + } + + /* send repeated start */ + iowrite8(KI2C_CONTROL_MEN | KI2C_CONTROL_MSTA | KI2C_CONTROL_RSTA, + ki2c->base + KI2C_CONTROL_REG); + + ret = ki2c_wait_for_mcf(ki2c); + if (ret < 0) { + dev_warn(&ki2c->pdev->dev, "%s wait for MCF err at 0x%02x!\n", + __func__, m->addr); + return ret; + } + + /* write target-address byte */ + ki2c_write_target_addr(ki2c, m); + + ret = ki2c_wait_for_data_ack(ki2c); + if (ret < 0) + dev_warn(&ki2c->pdev->dev, "%s wait for ACK err at 0x%02x!\n", + __func__, m->addr); + + return ret; +} + +static void ki2c_stop(struct ki2c *ki2c) +{ + iowrite8(KI2C_CONTROL_MEN, ki2c->base + KI2C_CONTROL_REG); + ki2c_wait_for_mcf(ki2c); +} + +static int ki2c_write(struct ki2c *ki2c, const u8 *data, int len) +{ + int ret; + + for (int i = 0; i < len; i++) { + /* write data byte */ + iowrite8(data[i], ki2c->base + KI2C_DATA_REG); + + ret = ki2c_wait_for_data_ack(ki2c); + if (ret < 0) + return ret; + } + + return 0; +} + +static int ki2c_read(struct ki2c *ki2c, u8 *data, int len) +{ + u8 control; + int ret; + + if (len == 0) + return 0; /* nothing to do */ + + control = KI2C_CONTROL_MEN | KI2C_CONTROL_MSTA; + + /* if just one byte => send tx-nack after transfer */ + if (len == 1) + control |= KI2C_CONTROL_TXAK; + + iowrite8(control, ki2c->base + KI2C_CONTROL_REG); + + /* dummy read to start transfer on bus */ + ioread8(ki2c->base + KI2C_DATA_REG); + + for (int i = 0; i < len; i++) { + ret = ki2c_wait_for_data(ki2c); + if (ret < 0) + return ret; + + /* send tx-nack after transfer of last byte */ + if (i == len - 2) + iowrite8(KI2C_CONTROL_MEN | KI2C_CONTROL_MSTA | KI2C_CONTROL_TXAK, + ki2c->base + KI2C_CONTROL_REG); + + /* switch to TX on last byte, so that reading DATA-register + * does not trigger another read transfer. + */ + if (i == len - 1) + iowrite8(KI2C_CONTROL_MEN | KI2C_CONTROL_MSTA | KI2C_CONTROL_MTX, + ki2c->base + KI2C_CONTROL_REG); + + /* read byte and start next transfer (if not last byte) */ + data[i] = ioread8(ki2c->base + KI2C_DATA_REG); + } + + return len; +} + +static int ki2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) +{ + struct ki2c *ki2c = i2c_get_adapdata(adap); + int ret; + + ret = ki2c_inuse_lock(ki2c); + if (ret < 0) + return ret; + + for (int i = 0; i < num; i++) { + struct i2c_msg *m = &msgs[i]; + + if (i == 0) + ret = ki2c_start_addr(ki2c, m); + else + ret = ki2c_repstart_addr(ki2c, m); + if (ret < 0) + break; + + if (m->flags & I2C_M_RD) + ret = ki2c_read(ki2c, m->buf, m->len); + else + ret = ki2c_write(ki2c, m->buf, m->len); + if (ret < 0) + break; + } + + ki2c_stop(ki2c); + + ki2c_inuse_unlock(ki2c); + + return (ret < 0) ? ret : num; +} + +static void ki2c_unregister_devices(struct ki2c *ki2c) +{ + for (int i = 0; i < ki2c->client_size; i++) { + struct i2c_client *client = ki2c->client[i]; + + if (client) + i2c_unregister_device(client); + } +} + +static int ki2c_register_devices(struct ki2c *ki2c, + struct i2c_keba_platform_data *pdata) +{ + /* register all I2C devices from platform_data array */ + for (int i = 0; i < ki2c->client_size; i++) { + struct i2c_client *client; + unsigned short const addr_list[2] = { pdata->info[i].addr, + I2C_CLIENT_END }; + + client = i2c_new_scanned_device(&ki2c->adapter, &pdata->info[i], + addr_list, NULL); + if (!IS_ERR(client)) { + ki2c->client[i] = client; + } else if (PTR_ERR(client) != -ENODEV) { + ki2c_unregister_devices(ki2c); + + return PTR_ERR(client); + } + } + + return 0; +} + +static u32 ki2c_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; +} + +static const struct i2c_algorithm ki2c_algo = { + .master_xfer = ki2c_xfer, + .functionality = ki2c_func, +}; + +static int ki2c_probe(struct platform_device *pdev) +{ + struct i2c_keba_platform_data *pdata; + struct device *dev = &pdev->dev; + struct i2c_adapter *adap; + struct resource *io; + struct ki2c *ki2c; + int ret; + + pdata = dev->platform_data; + if (pdata == 0) { + dev_err(dev, "Platform data not found!\n"); + return -ENODEV; + } + + ki2c = devm_kzalloc(dev, sizeof(*ki2c), GFP_KERNEL); + if (!ki2c) + return -ENOMEM; + ki2c->pdev = pdev; + ki2c->client = devm_kcalloc(dev, pdata->info_size, + sizeof(*ki2c->client), GFP_KERNEL); + if (!ki2c->client) + return -ENOMEM; + ki2c->client_size = pdata->info_size; + platform_set_drvdata(pdev, ki2c); + + io = platform_get_resource(pdev, IORESOURCE_MEM, 0); + ki2c->base = devm_ioremap_resource(dev, io); + if (IS_ERR(ki2c->base)) + return PTR_ERR(ki2c->base); + + /* enable controller */ + iowrite8(KI2C_CONTROL_MEN, ki2c->base + KI2C_CONTROL_REG); + + adap = &ki2c->adapter; + strscpy(adap->name, "KEBA I2C adapter", sizeof(adap->name)); + adap->owner = THIS_MODULE; + adap->class = I2C_CLASS_HWMON; + adap->algo = &ki2c_algo; + adap->dev.parent = dev; + + i2c_set_adapdata(adap, ki2c); + + /* reset bus before probing I2C devices */ + ret = ki2c_reset_bus(ki2c); + if (ret) { + dev_err(dev, "Failed to reset bus (%d)!\n", ret); + goto out_disable; + } + + ret = i2c_add_adapter(adap); + if (ret) { + dev_err(dev, "Failed to add adapter (%d)!\n", ret); + goto out_disable; + } + + ret = ki2c_register_devices(ki2c, pdata); + if (ret) { + dev_err(dev, "Failed to register devices (%d)!\n", ret); + goto out_delete; + } + + return 0; + +out_delete: + i2c_del_adapter(adap); +out_disable: + iowrite8(0, ki2c->base + KI2C_CONTROL_REG); + return ret; +} + +static int ki2c_remove(struct platform_device *pdev) +{ + struct ki2c *ki2c = platform_get_drvdata(pdev); + + ki2c_unregister_devices(ki2c); + + i2c_del_adapter(&ki2c->adapter); + + /* disable controller */ + iowrite8(0, ki2c->base + KI2C_CONTROL_REG); + + platform_set_drvdata(pdev, 0); + + return 0; +} + +static struct platform_device_id ki2c_devtype[] = { + { .name = KI2C }, + { } +}; +MODULE_DEVICE_TABLE(platform, ki2c_devtype); + +static struct platform_driver ki2c_driver = { + .driver = { + .name = KI2C, + }, + .probe = ki2c_probe, + .remove = ki2c_remove, +}; +module_platform_driver(ki2c_driver); + +MODULE_AUTHOR("Gerhard Engleder <eg@keba.com>"); +MODULE_DESCRIPTION("KEBA I2C bus controller driver"); +MODULE_LICENSE("GPL"); diff --git a/include/linux/platform_data/i2c-keba.h b/include/linux/platform_data/i2c-keba.h new file mode 100644 index 000000000000..99d54bcb6ed9 --- /dev/null +++ b/include/linux/platform_data/i2c-keba.h @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) KEBA AG 2012 + * Copyright (C) KEBA Industrial Automation Gmbh 2024 + * + * Platform data for KEBA I2C controller FPGA IP core + */ + +#ifndef __LINUX_PLATFORM_DATA_I2C_KEBA_H +#define __LINUX_PLATFORM_DATA_I2C_KEBA_H + +/** + * Platform data for KEBA I2C controller + * + * @info I2C devices to be probed + * @info_size size of info array + */ +struct i2c_keba_platform_data { + struct i2c_board_info *info; + int info_size; +}; + +#endif /* __LINUX_PLATFORM_DATA_I2C_KEBA_H */

[1/2] i2c: keba: Add KEBA I2C controller support

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