[PATCH v4 3/6] lib: utils/i2c: Add generic I2C configuration library
Xiang W
wxjstz at 126.com
Wed Nov 10 21:12:21 PST 2021
在 2021-11-10星期三的 22:30 +0530，Anup Patel写道：
> On Wed, Nov 10, 2021 at 6:32 PM Xiang W <wxjstz at 126.com> wrote:
> >
> > 在 2021-11-10星期三的 12:42 +0300，Nikita Shubin写道：
> > > From: Nikita Shubin <n.shubin at yadro.com>
> > >
> > > Helper library to keep track of registered I2C adapters,
> > > identified by dts offset, basic send/read functions and
> > > adapter configuration (enable, set dividers, etc...).
> > >
> > > Tested-by: Heinrich Schuchardt
> > > <heinrich.schuchardt at canonical.com>
> > > Reviewed-by: Alexandre Ghiti <alexandre.ghiti at canonical.com>
> > > Tested-by: Alexandre Ghiti <alexandre.ghiti at canonical.com>
> > > Signed-off-by: Nikita Shubin <n.shubin at yadro.com>
> > The i2c bus does not define register-related operations, these
> > interfaces should be renamed smbus
>
> I disagree with this suggestion, the existing read/write interface
> names are generic enough to send/receive an array of bytes.
> These are also suitable for reading EEPROMs or DDR SPD
> data, etc. I don't see why we should explicitly name it SMBUS
> and restrict it's use.
IIC is a particularly flexible bus. The standard only defines how to
address the device, but does not define how to access the registers in
the device. How to operate a device is defined by the device's data
sheet.
For example: 24LC64 EEPROM random read process
S: Start signal
Addr(7bit): address
R/W (1bit): read and write control signal
A/NA(1bit): Acknowledge signal
Data(8bit): data
P: STOP signal
[]: Indicates that data is transferred from the device to the host
S Addr R [A] Data [A] Data [A] S Addr R [Data] NA P
The first two Data are used to pass the address to be accessed, and the
latter Data is used to accept the read data
The current interface cannot operate 24LC64
Regards,
Xiang W
>
> Regards,
> Anup
>
> >
> > Regards,
> > Xiang W
> > > ---
> > > v3->v4:
> > > - fixed typo in include/sbi_utils/i2c/i2c.h
> > > - fixed inaccurate configure remove, leaked into patch 0004
> > > ---
> > > include/sbi_utils/i2c/i2c.h | 85
> > > +++++++++++++++++++++++++++++++++++++
> > > lib/utils/i2c/i2c.c | 75
> > > ++++++++++++++++++++++++++++++++
> > > lib/utils/i2c/objects.mk | 10 +++++
> > > 3 files changed, 170 insertions(+)
> > > create mode 100644 include/sbi_utils/i2c/i2c.h
> > > create mode 100644 lib/utils/i2c/i2c.c
> > > create mode 100644 lib/utils/i2c/objects.mk
> > >
> > > diff --git a/include/sbi_utils/i2c/i2c.h
> > > b/include/sbi_utils/i2c/i2c.h
> > > new file mode 100644
> > > index 0000000..79aeeb5
> > > --- /dev/null
> > > +++ b/include/sbi_utils/i2c/i2c.h
> > > @@ -0,0 +1,85 @@
> > > +/*
> > > + * SPDX-License-Identifier: BSD-2-Clause
> > > + *
> > > + * Copyright (c) 2021 YADRO
> > > + *
> > > + * Authors:
> > > + * Nikita Shubin <n.shubin at yadro.com>
> > > + */
> > > +
> > > +#ifndef __I2C_H__
> > > +#define __I2C_H__
> > > +
> > > +#include <sbi/sbi_types.h>
> > > +#include <sbi/sbi_list.h>
> > > +
> > > +/** Representation of a I2C adapter */
> > > +struct i2c_adapter {
> > > + /** Pointer to I2C driver owning this I2C adapter */
> > > + void *driver;
> > > +
> > > + /** Unique ID of the I2C adapter assigned by the driver
> > > */
> > > + int id;
> > > +
> > > + /**
> > > + * Send buffer to given address, register
> > > + *
> > > + * @return 0 on success and negative error code on
> > > failure
> > > + */
> > > + int (*write)(struct i2c_adapter *ia, uint8_t addr,
> > > uint8_t
> > > reg,
> > > + uint8_t *buffer, int len);
> > > +
> > > + /**
> > > + * Read buffer from given address, register
> > > + *
> > > + * @return 0 on success and negative error code on
> > > failure
> > > + */
> > > + int (*read)(struct i2c_adapter *ia, uint8_t addr, uint8_t
> > > reg,
> > > + uint8_t *buffer, int len);
> > > +
> > > + /** List */
> > > + struct sbi_dlist node;
> > > +};
> > > +
> > > +static inline struct i2c_adapter *to_i2c_adapter(struct
> > > sbi_dlist
> > > *node)
> > > +{
> > > + return container_of(node, struct i2c_adapter, node);
> > > +}
> > > +
> > > +/** Find a registered I2C adapter */
> > > +struct i2c_adapter *i2c_adapter_find(int id);
> > > +
> > > +/** Register I2C adapter */
> > > +int i2c_adapter_add(struct i2c_adapter *ia);
> > > +
> > > +/** Un-register I2C adapter */
> > > +void i2c_adapter_remove(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);
> > > +
> > > +/** Read from device on I2C adapter bus */
> > > +int i2c_adapter_read(struct i2c_adapter *ia, uint8_t addr,
> > > uint8_t
> > > reg,
> > > + uint8_t *buffer, int len);
> > > +
> > > +static inline int i2c_adapter_reg_write(struct i2c_adapter *ia,
> > > uint8_t addr,
> > > + uint8_t reg, uint8_t val)
> > > +{
> > > + return i2c_adapter_write(ia, addr, reg, &val, 1);
> > > +}
> > > +
> > > +static inline int i2c_adapter_reg_read(struct i2c_adapter *ia,
> > > uint8_t addr,
> > > + uint8_t reg, uint8_t *val)
> > > +{
> > > + uint8_t buf;
> > > + int ret = i2c_adapter_read(ia, addr, reg, &buf, 1);
> > > +
> > > + if (ret)
> > > + return ret;
> > > +
> > > + *val = buf;
> > > + return 0;
> > > +}
> > > +
> > > +#endif
> > > diff --git a/lib/utils/i2c/i2c.c b/lib/utils/i2c/i2c.c
> > > new file mode 100644
> > > index 0000000..1f5072c
> > > --- /dev/null
> > > +++ b/lib/utils/i2c/i2c.c
> > > @@ -0,0 +1,75 @@
> > > +/*
> > > + * SPDX-License-Identifier: BSD-2-Clause
> > > + *
> > > + * Copyright (c) 2021 YADRO
> > > + *
> > > + * Authors:
> > > + * Nikita Shubin <n.shubin at yadro.com>
> > > + *
> > > + * derivate: lib/utils/gpio/gpio.c
> > > + * Authors:
> > > + * Anup Patel <anup.patel at wdc.com>
> > > + */
> > > +
> > > +#include <sbi/sbi_error.h>
> > > +#include <sbi_utils/i2c/i2c.h>
> > > +
> > > +static SBI_LIST_HEAD(i2c_adapters_list);
> > > +
> > > +struct i2c_adapter *i2c_adapter_find(int id)
> > > +{
> > > + struct sbi_dlist *pos;
> > > +
> > > + sbi_list_for_each(pos, &(i2c_adapters_list)) {
> > > + struct i2c_adapter *adap = to_i2c_adapter(pos);
> > > +
> > > + if (adap->id == id)
> > > + return adap;
> > > + }
> > > +
> > > + return NULL;
> > > +}
> > > +
> > > +int i2c_adapter_add(struct i2c_adapter *ia)
> > > +{
> > > + if (!ia)
> > > + return SBI_EINVAL;
> > > +
> > > + if (i2c_adapter_find(ia->id))
> > > + return SBI_EALREADY;
> > > +
> > > + sbi_list_add(&(ia->node), &(i2c_adapters_list));
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +void i2c_adapter_remove(struct i2c_adapter *ia)
> > > +{
> > > + if (!ia)
> > > + return;
> > > +
> > > + sbi_list_del(&(ia->node));
> > > +}
> > > +
> > > +int i2c_adapter_write(struct i2c_adapter *ia, uint8_t addr,
> > > uint8_t
> > > reg,
> > > + uint8_t *buffer, int len)
> > > +{
> > > + if (!ia)
> > > + return SBI_EINVAL;
> > > + if (!ia->write)
> > > + return SBI_ENOSYS;
> > > +
> > > + return ia->write(ia, addr, reg, buffer, len);
> > > +}
> > > +
> > > +
> > > +int i2c_adapter_read(struct i2c_adapter *ia, uint8_t addr,
> > > uint8_t
> > > reg,
> > > + uint8_t *buffer, int len)
> > > +{
> > > + if (!ia)
> > > + return SBI_EINVAL;
> > > + if (!ia->read)
> > > + return SBI_ENOSYS;
> > > +
> > > + return ia->read(ia, addr, reg, buffer, len);
> > > +}
> > > diff --git a/lib/utils/i2c/objects.mk b/lib/utils/i2c/objects.mk
> > > new file mode 100644
> > > index 0000000..16a70da
> > > --- /dev/null
> > > +++ b/lib/utils/i2c/objects.mk
> > > @@ -0,0 +1,10 @@
> > > +#
> > > +# SPDX-License-Identifier: BSD-2-Clause
> > > +#
> > > +# Copyright (c) 2021 YADRO
> > > +#
> > > +# Authors:
> > > +# Nikita Shubin <n.shubin at yadro.com>
> > > +#
> > > +
> > > +libsbiutils-objs-y += i2c/i2c.o
> > > --
> > > 2.31.1
> > >
> > >
> >
> >
> >
> > --
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