[v2,0/3] misc: aspeed-lpc-ctrl fixes

Hi Greg,

Once Andrew has acked the bindings I think this is ready to go.

v2: Fix binding layout and add Rob's ack

These patches were developed when testing upstream Linux with OpenBMC on
Romulus. We need to ensure the LPC clock is enabled, now that the clock
driver turns off any unused clocks. We also need to enable the LPC
firmware cycles bit as we do not intend to upstream any mach-aspeed
hacks.

There was no existing binding document for the LPC host interface
controller, so I wrote one that includes the required clock description.

Joel Stanley (3):
  dt-bindings: aspeed-lpc: Document LPC Host Interface Controller
  misc: aspeed-lpc: Request and enable LPC clock
  misc: aspeed-lpc-ctrl: Enable FWH and A2H bridge cycles

 .../devicetree/bindings/mfd/aspeed-lpc.txt         | 41 ++++++++++++++++++++
 drivers/misc/aspeed-lpc-ctrl.c                     | 44 +++++++++++++++++++---
 2 files changed, 80 insertions(+), 5 deletions(-)

On Mon, 2018-02-19 at 17:54 +1030, Joel Stanley wrote:
> To date this driver has relied on prevous state from out of tree hacks
> and vendor u-boot trees in order to have the host be able to access
> data over the LPC bus.
> 
> Now we explicitly enable the AHB to LPC bridge and FWH cycles from when
> the user first configures the address to map. We chose to do this then
> as before that time there is no way for the kernel to know where it is
> safe to point the LPC window.
> 
> Tested-by: Lei YU <mine260309@gmail.com>
> Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
> Signed-off-by: Joel Stanley <joel@jms.id.au>

Reviewed-by: Cyril Bur <cyrilbur@gmail.com>

> ---
>  drivers/misc/aspeed-lpc-ctrl.c | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/misc/aspeed-lpc-ctrl.c b/drivers/misc/aspeed-lpc-ctrl.c
> index 1827b7aa6674..a024f8042259 100644
> --- a/drivers/misc/aspeed-lpc-ctrl.c
> +++ b/drivers/misc/aspeed-lpc-ctrl.c
> @@ -21,6 +21,10 @@
>  
>  #define DEVICE_NAME	"aspeed-lpc-ctrl"
>  
> +#define HICR5 0x0
> +#define HICR5_ENL2H	BIT(8)
> +#define HICR5_ENFWH	BIT(10)
> +
>  #define HICR7 0x8
>  #define HICR8 0xc
>  
> @@ -155,8 +159,18 @@ static long aspeed_lpc_ctrl_ioctl(struct file *file, unsigned int cmd,
>  		if (rc)
>  			return rc;
>  
> -		return regmap_write(lpc_ctrl->regmap, HICR8,
> -			(~(map.size - 1)) | ((map.size >> 16) - 1));
> +		rc = regmap_write(lpc_ctrl->regmap, HICR8,
> +				(~(map.size - 1)) | ((map.size >> 16) - 1));
> +		if (rc)
> +			return rc;
> +
> +		/*
> +		 * Enable LPC FHW cycles. This is required for the host to
> +		 * access the regions specified.
> +		 */
> +		return regmap_update_bits(lpc_ctrl->regmap, HICR5,
> +				HICR5_ENFWH | HICR5_ENL2H,
> +				HICR5_ENFWH | HICR5_ENL2H);
>  	}
>  
>  	return -EINVAL;
--
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On Mon, 2018-02-19 at 17:54 +1030, Joel Stanley wrote:
> The LPC device needs to ensure it's clock is enabled before it can do
> anything.
> 
> In the past the clock was enabled and left running by u-boot, however
> Linux now has an upstream clock driver that disables unused clocks.
> 
> Tested-by: Lei YU <mine260309@gmail.com>
> Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
> Signed-off-by: Joel Stanley <joel@jms.id.au>

Reviewed-by: Cyril Bur <cyrilbur@gmail.com>

> ---
>  drivers/misc/aspeed-lpc-ctrl.c | 26 +++++++++++++++++++++++---
>  1 file changed, 23 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/misc/aspeed-lpc-ctrl.c b/drivers/misc/aspeed-lpc-ctrl.c
> index b5439643f54b..1827b7aa6674 100644
> --- a/drivers/misc/aspeed-lpc-ctrl.c
> +++ b/drivers/misc/aspeed-lpc-ctrl.c
> @@ -7,6 +7,7 @@
>   * 2 of the License, or (at your option) any later version.
>   */
>  
> +#include <linux/clk.h>
>  #include <linux/mfd/syscon.h>
>  #include <linux/miscdevice.h>
>  #include <linux/mm.h>
> @@ -26,6 +27,7 @@
>  struct aspeed_lpc_ctrl {
>  	struct miscdevice	miscdev;
>  	struct regmap		*regmap;
> +	struct clk		*clk;
>  	phys_addr_t		mem_base;
>  	resource_size_t		mem_size;
>  	u32		pnor_size;
> @@ -221,16 +223,33 @@ static int aspeed_lpc_ctrl_probe(struct platform_device *pdev)
>  		return -ENODEV;
>  	}
>  
> +	lpc_ctrl->clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(lpc_ctrl->clk)) {
> +		dev_err(dev, "couldn't get clock\n");
> +		return PTR_ERR(lpc_ctrl->clk);
> +	}
> +	rc = clk_prepare_enable(lpc_ctrl->clk);
> +	if (rc) {
> +		dev_err(dev, "couldn't enable clock\n");
> +		return rc;
> +	}
> +
>  	lpc_ctrl->miscdev.minor = MISC_DYNAMIC_MINOR;
>  	lpc_ctrl->miscdev.name = DEVICE_NAME;
>  	lpc_ctrl->miscdev.fops = &aspeed_lpc_ctrl_fops;
>  	lpc_ctrl->miscdev.parent = dev;
>  	rc = misc_register(&lpc_ctrl->miscdev);
> -	if (rc)
> +	if (rc) {
>  		dev_err(dev, "Unable to register device\n");
> -	else
> -		dev_info(dev, "Loaded at %pr\n", &resm);
> +		goto err;
> +	}
> +
> +	dev_info(dev, "Loaded at %pr\n", &resm);
> +
> +	return 0;
>  
> +err:
> +	clk_disable_unprepare(lpc_ctrl->clk);
>  	return rc;
>  }
>  
> @@ -239,6 +258,7 @@ static int aspeed_lpc_ctrl_remove(struct platform_device *pdev)
>  	struct aspeed_lpc_ctrl *lpc_ctrl = dev_get_drvdata(&pdev->dev);
>  
>  	misc_deregister(&lpc_ctrl->miscdev);
> +	clk_disable_unprepare(lpc_ctrl->clk);
>  
>  	return 0;
>  }
--
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