[PATCH v6 1/2] i2c: add support for microchip fpga i2c controllers
Wolfram Sang
wsa at kernel.org
Wed Jul 6 00:19:20 PDT 2022
Hi Conor,
thank you for sending this driver.
On Tue, Jun 21, 2022 at 08:42:38AM +0100, Conor Dooley wrote:
> Add Microchip CoreI2C i2c controller support. This driver supports the
> "hard" i2c controller on the Microchip PolarFire SoC & the basic feature
> set for "soft" i2c controller implemtations in the FPGA fabric.
>
> Co-developed-by: Daire McNamara <daire.mcnamara at microchip.com>
> Signed-off-by: Daire McNamara <daire.mcnamara at microchip.com>
> Signed-off-by: Conor Dooley <conor.dooley at microchip.com>
Where are the bindings? Are they already on the way upstream?
> drivers/i2c/busses/i2c-microchip-core.c | 486 ++++++++++++++++++++++++
The biggest remark I have is to rename the driver a little. Usually a
"-core" suffix means that there are other drivers like "-platform" or
"-pci" use this core. Would "i2c-microchip-fpga" or
"i2c-microchip-corei2c" work for you?
> +#include <linux/clk.h>
> +#include <linux/clkdev.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/iopoll.h>
Do you really need that?
...
> +static irqreturn_t mchp_corei2c_handle_isr(struct mchp_corei2c_dev *idev)
> +{
> + u32 status = idev->isr_status;
> + u8 ctrl;
> + bool last_byte = false, finished = false;
> +
> + if (!idev->buf)
> + return IRQ_NONE;
> +
> + switch (status) {
> + case STATUS_M_START_SENT:
> + case STATUS_M_REPEATED_START_SENT:
> + ctrl = readb(idev->base + CORE_I2C_CTRL);
> + ctrl &= ~CTRL_STA;
> + writeb(idev->addr, idev->base + CORE_I2C_DATA);
> + writeb(ctrl, idev->base + CORE_I2C_CTRL);
> + if (idev->msg_len <= 0)
> + finished = true;
How can it happen that len is < 0? Wouldn't that be an error case?
...
> +static u32 mchp_corei2c_func(struct i2c_adapter *adap)
> +{
> + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
Have you testes SMBUS_QUICK as well?
...
> + idev->dev = &pdev->dev;
> + init_completion(&idev->msg_complete);
> + spin_lock_init(&idev->lock);
You never use this lock.
...
> + idev->adapter.owner = THIS_MODULE;
> + idev->adapter.algo = &mchp_corei2c_algo;
> + idev->adapter.dev.parent = &pdev->dev;
> + idev->adapter.dev.of_node = pdev->dev.of_node;
> + idev->adapter.timeout = MICROCHIP_I2C_TIMEOUT;
Simply use HZ here?
All in all, only minor stuff. Driver looks really good in general.
Thanks and happy hacking,
Wolfram
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