[PATCH v3 5/6] lib: utils/i2c: Add minimal SiFive I2C driver

Alexandre Ghiti alexandre.ghiti at canonical.com
Tue Nov 9 23:39:31 PST 2021


On Tue, Nov 9, 2021 at 1:41 PM Nikita Shubin <nikita.shubin at maquefel.me> wrote:
>
> From: Nikita Shubin <n.shubin at yadro.com>
>
> Minimum SiFive I2C driver to read/send bytes over I2C bus.
>
> This allows querying information and perform operation of onboard PMIC,
> as well as power-off and reset.
>
> Signed-off-by: Nikita Shubin <n.shubin at yadro.com>
> ---
> v2->v3:
> - fixed setreg/getreg reg type
> - fixed polling function
> - dropped configure
> - dropped unused defines
> ---
>  include/sbi_utils/i2c/i2c.h    |  12 --
>  lib/utils/i2c/fdt_i2c.c        |   3 +
>  lib/utils/i2c/fdt_i2c_sifive.c | 262 +++++++++++++++++++++++++++++++++
>  lib/utils/i2c/objects.mk       |   1 +
>  4 files changed, 266 insertions(+), 12 deletions(-)
>  create mode 100644 lib/utils/i2c/fdt_i2c_sifive.c
>
> diff --git a/include/sbi_utils/i2c/i2c.h b/include/sbi_utils/i2c/i2c.h
> index 09e5f0e..79aeeb5 100644
> --- a/include/sbi_utils/i2c/i2c.h
> +++ b/include/sbi_utils/i2c/i2c.h
> @@ -21,15 +21,6 @@ struct i2c_adapter {
>         /** Uniquie ID of the I2C adapter assigned by the driver */
>         int id;
>
> -       /**
> -        * Configure I2C adapter
> -        *
> -        * Enable, set dividers, etc...
> -        *
> -        * @return 0 on success and negative error code on failure
> -        */
> -       int (*configure)(struct i2c_adapter *ia);
> -
>         /**
>          * Send buffer to given address, register
>          *
> @@ -64,9 +55,6 @@ int i2c_adapter_add(struct i2c_adapter *ia);
>  /** Un-register I2C adapter */
>  void i2c_adapter_remove(struct i2c_adapter *ia);
>
> -/** Configure I2C adapter prior to send/read */
> -int i2c_adapter_configure(struct i2c_adapter *ia);
> -
>  /** Send to device on I2C adapter bus */
>  int i2c_adapter_write(struct i2c_adapter *ia, uint8_t addr, uint8_t reg,
>                       uint8_t *buffer, int len);
> diff --git a/lib/utils/i2c/fdt_i2c.c b/lib/utils/i2c/fdt_i2c.c
> index 3182f56..d4ec6a3 100644
> --- a/lib/utils/i2c/fdt_i2c.c
> +++ b/lib/utils/i2c/fdt_i2c.c
> @@ -18,7 +18,10 @@
>
>  #include <sbi/sbi_console.h>
>
> +extern struct fdt_i2c_adapter fdt_i2c_adapter_sifive;
> +
>  static struct fdt_i2c_adapter *i2c_adapter_drivers[] = {
> +       &fdt_i2c_adapter_sifive
>  };
>
>  static int fdt_i2c_adapter_init(void *fdt, int nodeoff)
> diff --git a/lib/utils/i2c/fdt_i2c_sifive.c b/lib/utils/i2c/fdt_i2c_sifive.c
> new file mode 100644
> index 0000000..404eda4
> --- /dev/null
> +++ b/lib/utils/i2c/fdt_i2c_sifive.c
> @@ -0,0 +1,262 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2021 YADRO
> + *
> + * Authors:
> + *   Nikita Shubin <nshubin at yadro.com>
> + */
> +
> +#include <sbi/riscv_io.h>
> +#include <sbi/sbi_error.h>
> +#include <sbi/sbi_timer.h>
> +#include <sbi_utils/fdt/fdt_helper.h>
> +#include <sbi_utils/i2c/fdt_i2c.h>
> +
> +#define SIFIVE_I2C_ADAPTER_MAX 2
> +
> +#define SIFIVE_I2C_PRELO       0x00
> +#define SIFIVE_I2C_PREHI       0x04
> +#define SIFIVE_I2C_CTR         0x08
> +#define SIFIVE_I2C_TXR         0x00c
> +#define SIFIVE_I2C_RXR         SIFIVE_I2C_TXR
> +#define SIFIVE_I2C_CR          0x010
> +#define SIFIVE_I2C_SR          SIFIVE_I2C_CR
> +
> +#define SIFIVE_I2C_CTR_IEN     (1 << 6)
> +#define SIFIVE_I2C_CTR_EN      (1 << 7)
> +
> +#define SIFIVE_I2C_CMD_IACK    (1 << 0)
> +#define SIFIVE_I2C_CMD_ACK     (1 << 3)
> +#define SIFIVE_I2C_CMD_WR      (1 << 4)
> +#define SIFIVE_I2C_CMD_RD      (1 << 5)
> +#define SIFIVE_I2C_CMD_STO     (1 << 6)
> +#define SIFIVE_I2C_CMD_STA     (1 << 7)
> +
> +#define SIFIVE_I2C_STATUS_IF   (1 << 0)
> +#define SIFIVE_I2C_STATUS_TIP  (1 << 1)
> +#define SIFIVE_I2C_STATUS_AL   (1 << 5)
> +#define SIFIVE_I2C_STATUS_BUSY (1 << 6)
> +#define SIFIVE_I2C_STATUS_RXACK        (1 << 7)
> +
> +#define SIFIVE_I2C_WRITE_BIT   (0 << 0)
> +#define SIFIVE_I2C_READ_BIT    (1 << 0)
> +
> +struct sifive_i2c_adapter {
> +       unsigned long addr;
> +       struct i2c_adapter adapter;
> +};
> +
> +static unsigned int sifive_i2c_adapter_count;
> +static struct sifive_i2c_adapter sifive_i2c_adapter_array[SIFIVE_I2C_ADAPTER_MAX];
> +
> +extern struct fdt_i2c_adapter fdt_i2c_adapter_sifive;
> +
> +static inline void sifive_i2c_setreg(struct sifive_i2c_adapter *adap,
> +                                    uint8_t reg, uint8_t value)
> +{
> +       writel(value, (volatile void *)adap->addr + reg);
> +}
> +
> +static inline uint8_t sifive_i2c_getreg(struct sifive_i2c_adapter *adap,
> +                                       uint8_t reg)
> +{
> +       return readl((volatile void *)adap->addr + reg);
> +}
> +
> +static int sifive_i2c_adapter_rxack(struct sifive_i2c_adapter *adap)
> +{
> +       uint8_t val = sifive_i2c_getreg(adap, SIFIVE_I2C_SR);
> +
> +       if (val & SIFIVE_I2C_STATUS_RXACK)
> +               return SBI_EIO;
> +
> +       return 0;
> +}
> +
> +static int sifive_i2c_adapter_poll(struct sifive_i2c_adapter *adap, uint32_t mask)
> +{
> +       unsigned int timeout = 1; // [msec]
> +       int count = 0;
> +       uint8_t val;
> +
> +       sbi_timer_udelay(80); // worst case if bus speed is 100 kHz
> +
> +       do {
> +               val = sifive_i2c_getreg(adap, SIFIVE_I2C_SR);
> +               if (!(val & mask))
> +                       return 0;
> +
> +               sbi_timer_udelay(1);
> +               count += 1;
> +               if (count == (timeout * 1000))
> +                       return SBI_ETIMEDOUT;
> +       } while (1);
> +}
> +
> +#define sifive_i2c_adapter_poll_tip(adap) sifive_i2c_adapter_poll(adap, SIFIVE_I2C_STATUS_TIP)
> +#define sifive_i2c_adapter_poll_busy(adap) sifive_i2c_adapter_poll(adap, SIFIVE_I2C_STATUS_BUSY)
> +
> +static int sifive_i2c_adapter_start(struct sifive_i2c_adapter *adap, uint8_t addr, uint8_t bit)
> +{
> +       uint8_t val = (addr << 1) | bit;
> +
> +       sifive_i2c_setreg(adap, SIFIVE_I2C_TXR, val);
> +       val = SIFIVE_I2C_CMD_STA | SIFIVE_I2C_CMD_WR | SIFIVE_I2C_CMD_IACK;
> +       sifive_i2c_setreg(adap, SIFIVE_I2C_CR, val);
> +
> +       return sifive_i2c_adapter_poll_tip(adap);
> +}
> +
> +static int sifive_i2c_adapter_write(struct i2c_adapter *ia, uint8_t addr,
> +                                   uint8_t reg, uint8_t *buffer, int len)
> +{
> +       struct sifive_i2c_adapter *adap =
> +               container_of(ia, struct sifive_i2c_adapter, adapter);
> +       int rc = sifive_i2c_adapter_start(adap, addr, SIFIVE_I2C_WRITE_BIT);
> +
> +       if (rc)
> +               return rc;
> +
> +       rc = sifive_i2c_adapter_rxack(adap);
> +       if (rc)
> +               return rc;
> +
> +       /* set register address */
> +       sifive_i2c_setreg(adap, SIFIVE_I2C_TXR, reg);
> +       sifive_i2c_setreg(adap, SIFIVE_I2C_CR, SIFIVE_I2C_CMD_WR | SIFIVE_I2C_CMD_IACK);
> +       rc = sifive_i2c_adapter_poll_tip(adap);
> +       if (rc)
> +               return rc;
> +
> +       rc = sifive_i2c_adapter_rxack(adap);
> +       if (rc)
> +               return rc;
> +
> +       /* set value */
> +       while (len) {
> +               sifive_i2c_setreg(adap, SIFIVE_I2C_TXR, *buffer);
> +               sifive_i2c_setreg(adap, SIFIVE_I2C_CR, SIFIVE_I2C_CMD_WR | SIFIVE_I2C_CMD_IACK);
> +
> +               rc = sifive_i2c_adapter_poll_tip(adap);
> +               if (rc)
> +                       return rc;
> +
> +               rc = sifive_i2c_adapter_rxack(adap);
> +               if (rc)
> +                       return rc;
> +
> +               buffer++;
> +               len--;
> +       }
> +
> +       sifive_i2c_setreg(adap, SIFIVE_I2C_CR, SIFIVE_I2C_CMD_STO | SIFIVE_I2C_CMD_IACK);
> +
> +       /* poll BUSY instead of ACK*/
> +       rc = sifive_i2c_adapter_poll_busy(adap);
> +       if (rc)
> +               return rc;
> +
> +       sifive_i2c_setreg(adap, SIFIVE_I2C_CR, SIFIVE_I2C_CMD_IACK);
> +
> +       return 0;
> +}
> +
> +static int sifive_i2c_adapter_read(struct i2c_adapter *ia, uint8_t addr,
> +                                  uint8_t reg, uint8_t *buffer, int len)
> +{
> +       struct sifive_i2c_adapter *adap =
> +               container_of(ia, struct sifive_i2c_adapter, adapter);
> +       int rc;
> +
> +       rc = sifive_i2c_adapter_start(adap, addr, SIFIVE_I2C_WRITE_BIT);
> +       if (rc)
> +               return rc;
> +
> +       rc = sifive_i2c_adapter_rxack(adap);
> +       if (rc)
> +               return rc;
> +
> +       sifive_i2c_setreg(adap, SIFIVE_I2C_TXR, reg);
> +       sifive_i2c_setreg(adap, SIFIVE_I2C_CR, SIFIVE_I2C_CMD_WR | SIFIVE_I2C_CMD_IACK);
> +
> +       rc = sifive_i2c_adapter_poll_tip(adap);
> +       if (rc)
> +               return rc;
> +
> +       rc = sifive_i2c_adapter_rxack(adap);
> +       if (rc)
> +               return rc;
> +
> +       /* setting addr with high 0 bit */
> +       rc = sifive_i2c_adapter_start(adap, addr, SIFIVE_I2C_READ_BIT);
> +       if (rc)
> +               return rc;
> +
> +       rc = sifive_i2c_adapter_rxack(adap);
> +       if (rc)
> +               return rc;
> +
> +       while (len) {
> +               if (len == 1)
> +                       sifive_i2c_setreg(adap, SIFIVE_I2C_CR, SIFIVE_I2C_CMD_ACK | SIFIVE_I2C_CMD_RD | SIFIVE_I2C_CMD_IACK);
> +               else
> +                       sifive_i2c_setreg(adap, SIFIVE_I2C_CR, SIFIVE_I2C_CMD_RD | SIFIVE_I2C_CMD_IACK);
> +
> +               rc = sifive_i2c_adapter_poll_tip(adap);
> +               if (rc)
> +                       return rc;
> +
> +               *buffer = sifive_i2c_getreg(adap, SIFIVE_I2C_RXR);
> +               buffer++;
> +               len--;
> +       }
> +
> +       sifive_i2c_setreg(adap, SIFIVE_I2C_CR, SIFIVE_I2C_CMD_STO | SIFIVE_I2C_CMD_IACK);
> +       rc = sifive_i2c_adapter_poll_busy(adap);
> +       if (rc)
> +               return rc;
> +
> +       sifive_i2c_setreg(adap, SIFIVE_I2C_CR, SIFIVE_I2C_CMD_IACK);
> +
> +       return 0;
> +}
> +
> +static int sifive_i2c_init(void *fdt, int nodeoff,
> +                           const struct fdt_match *match)
> +{
> +       int rc;
> +       struct sifive_i2c_adapter *adapter;
> +       uint64_t addr;
> +
> +       if (sifive_i2c_adapter_count >= SIFIVE_I2C_ADAPTER_MAX)
> +               return SBI_ENOSPC;
> +
> +       adapter = &sifive_i2c_adapter_array[sifive_i2c_adapter_count];
> +
> +       rc = fdt_get_node_addr_size(fdt, nodeoff, 0, &addr, NULL);
> +       if (rc)
> +               return rc;
> +
> +       adapter->addr = addr;
> +       adapter->adapter.driver = &fdt_i2c_adapter_sifive;
> +       adapter->adapter.id = nodeoff;
> +       adapter->adapter.write = sifive_i2c_adapter_write;
> +       adapter->adapter.read = sifive_i2c_adapter_read;
> +       rc = i2c_adapter_add(&adapter->adapter);
> +       if (rc)
> +               return rc;
> +
> +       sifive_i2c_adapter_count++;
> +       return 0;
> +}
> +
> +static const struct fdt_match sifive_i2c_match[] = {
> +       { .compatible = "sifive,i2c0" },
> +       { },
> +};
> +
> +struct fdt_i2c_adapter fdt_i2c_adapter_sifive = {
> +       .match_table = sifive_i2c_match,
> +       .init = sifive_i2c_init,
> +};
> diff --git a/lib/utils/i2c/objects.mk b/lib/utils/i2c/objects.mk
> index 06baa65..d52ab18 100644
> --- a/lib/utils/i2c/objects.mk
> +++ b/lib/utils/i2c/objects.mk
> @@ -9,3 +9,4 @@
>
>  libsbiutils-objs-y += i2c/i2c.o
>  libsbiutils-objs-y += i2c/fdt_i2c.o
> +libsbiutils-objs-y += i2c/fdt_i2c_sifive.o
> --
> 2.31.1
>

You can add:

Reviewed-by: Alexandre Ghiti <alexandre.ghiti at canonical.com>
Tested-by: Alexandre Ghiti <alexandre.ghiti at canonical.com>

Thanks,

Alex



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