Subject: Re: [PATCH 2/3] i2c-mpc: add support for the MPC512x processors from Freescale

From: Wolfgang Grandegger <[email-masked]>
Date: Mon, 25 Jan 2010 13:06:36 +0100

Hi Wolfram,

Wolfram Sang wrote:
> Hi Wolfgang,
> 
> On Mon, Jan 25, 2010 at 09:27:08AM +0100, Wolfgang Grandegger wrote:
>> From: Wolfgang Grandegger <[email-masked]>
>>
>> The "setclock" initialization functions have been renamed to "setup"
>> because I2C interrupts must be enabled for the MPC512x. This requires
>> to handle "fsl,preserve-clocking" in a slighly different way. Also,
>> the old settings are now reported calling dev_dbg(). For the MPC512x
>> the clock setup function of the MPC52xx can be re-used.
>>
>> Signed-off-by: Wolfgang Grandegger <[email-masked]>
>> ---
>>  drivers/i2c/busses/Kconfig   |    9 ++--
>>  drivers/i2c/busses/i2c-mpc.c |  122 ++++++++++++++++++++++++++++++------------
>>  2 files changed, 93 insertions(+), 38 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
>> index 5f318ce..f481f30 100644
>> --- a/drivers/i2c/busses/Kconfig
>> +++ b/drivers/i2c/busses/Kconfig
>> @@ -418,13 +418,14 @@ config I2C_IXP2000
>>  	  instead.
>>  
>>  config I2C_MPC
>> -	tristate "MPC107/824x/85xx/52xx/86xx"
>> +	tristate "MPC107/824x/85xx/512x/52xx/86xx"
>>  	depends on PPC32
>>  	help
>>  	  If you say yes to this option, support will be included for the
>> -	  built-in I2C interface on the MPC107/Tsi107/MPC8240/MPC8245 and
>> -	  MPC85xx/MPC8641 family processors. The driver may also work on 52xx
>> -	  family processors, though interrupts are known not to work.
>> +	  built-in I2C interface on the MPC107/Tsi107/MPC8240/MPC8245,
>> +	  MPC85xx/MPC8641 and MPC512x family processors. The driver may
>> +	  also work on 52xx family processors, though interrupts are known
>> +	  not to work.
> 
> Opinion poll: Can we remove the "may work" sentence while we are here? It has
> worked fine for years. BTW, which interrupts are meant here (from I2C slaves?
> interrupts of the controller?)?

I first wanted to remove this sentence but as I was not sure what it's
exact meaning... Anyway, it's confusing and I would remove it.

>>  	  This driver can also be built as a module.  If so, the module
>>  	  will be called i2c-mpc.
>> diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
>> index 2cb864e..70c3e5d 100644
>> --- a/drivers/i2c/busses/i2c-mpc.c
>> +++ b/drivers/i2c/busses/i2c-mpc.c
>> @@ -67,9 +67,8 @@ struct mpc_i2c_divider {
>>  };
>>  
>>  struct mpc_i2c_data {
>> -	void (*setclock)(struct device_node *node,
>> -			 struct mpc_i2c *i2c,
>> -			 u32 clock, u32 prescaler);
>> +	void (*setup)(struct device_node *node, struct mpc_i2c *i2c,
>> +		      u32 clock, u32 prescaler);
>>  	u32 prescaler;
>>  };
>>  
>> @@ -164,7 +163,7 @@ static int i2c_wait(struct mpc_i2c *i2c, unsigned timeout, int writing)
>>  	return 0;
>>  }
>>  
>> -#ifdef CONFIG_PPC_MPC52xx
>> +#if defined(CONFIG_PPC_MPC52xx) || defined(CONFIG_PPC_MPC512x)
>>  static const struct __devinitdata mpc_i2c_divider mpc_i2c_dividers_52xx[] = {
>>  	{20, 0x20}, {22, 0x21}, {24, 0x22}, {26, 0x23},
>>  	{28, 0x24}, {30, 0x01}, {32, 0x25}, {34, 0x02},
>> @@ -216,12 +215,18 @@ static int __devinit mpc_i2c_get_fdr_52xx(struct device_node *node, u32 clock,
>>  	return div ? (int)div->fdr : -EINVAL;
>>  }
>>  
>> -static void __devinit mpc_i2c_setclock_52xx(struct device_node *node,
>> -					    struct mpc_i2c *i2c,
>> -					    u32 clock, u32 prescaler)
>> +static void __devinit mpc_i2c_setup_52xx(struct device_node *node,
>> +					 struct mpc_i2c *i2c,
>> +					 u32 clock, u32 prescaler)
>>  {
>>  	int ret, fdr;
>>  
>> +	if (clock == -1) {
> 
> Could we use 0 for 'no_clock'? This would make the above statement simply

"0" is already used to maintain backward compatibility setting a safe
divider.

> 	if (!clock)
> 
> and saves us using -1 with a u32.
> 
>> +		dev_dbg(i2c->dev, "using fdr %d\n",
>> +			readb(i2c->base + MPC_I2C_FDR));
>> +		return;	/* preserve clocking */
>> +	}
>> +
>>  	ret = mpc_i2c_get_fdr_52xx(node, clock, prescaler);
>>  	fdr = (ret >= 0) ? ret : 0x3f; /* backward compatibility */
>>  
>> @@ -230,13 +235,50 @@ static void __devinit mpc_i2c_setclock_52xx(struct device_node *node,
>>  	if (ret >= 0)
>>  		dev_info(i2c->dev, "clock %d Hz (fdr=%d)\n", clock, fdr);
>>  }
>> -#else /* !CONFIG_PPC_MPC52xx */
>> -static void __devinit mpc_i2c_setclock_52xx(struct device_node *node,
>> -					    struct mpc_i2c *i2c,
>> -					    u32 clock, u32 prescaler)
>> +#else /* !(CONFIG_PPC_MPC52xx || CONFIG_PPC_MPC512x) */
>> +static void __devinit mpc_i2c_setup_52xx(struct device_node *node,
>> +					 struct mpc_i2c *i2c,
>> +					 u32 clock, u32 prescaler)
>> +{
>> +}
>> +#endif /* CONFIG_PPC_MPC52xx || CONFIG_PPC_MPC512x */
>> +
>> +#ifdef CONFIG_PPC_MPC512x
>> +static void __devinit mpc_i2c_setup_512x(struct device_node *node,
>> +					 struct mpc_i2c *i2c,
>> +					 u32 clock, u32 prescaler)
>> +{
>> +	struct device_node *node_ctrl;
>> +	void __iomem *ctrl;
>> +	const u32 *pval;
>> +	u32 idx;
>> +
>> +	/* Enable I2C interrupts for mpc5121 */
>> +	node_ctrl = of_find_compatible_node(NULL, NULL,
>> +					    "fsl,mpc5121-i2c-ctrl");
>> +	if (node_ctrl) {
>> +		ctrl = of_iomap(node_ctrl, 0);
>> +		if (ctrl) {
>> +
>> +			/* Interrupt enable bits for i2c-0/1/2: bit 24/26/28 */
>> +			pval = of_get_property(node, "reg", NULL);
>> +			idx = (*pval & 0xff) / 0x20;
>> +			setbits32(ctrl, 1 << (24 + idx * 2));
>> +			iounmap(ctrl);
>> +		}
>> +		of_node_put(node_ctrl);
>> +	}
>> +
>> +	/* The clock setup for the 52xx works also fine for the 512x */
>> +	mpc_i2c_setup_52xx(node, i2c, clock, prescaler);
>> +}
>> +#else /* CONFIG_PPC_MPC512x */
>> +static void __devinit mpc_i2c_setup_512x(struct device_node *node,
>> +					 struct mpc_i2c *i2c,
>> +					 u32 clock, u32 prescaler)
>>  {
>>  }
>> -#endif /* CONFIG_PPC_MPC52xx*/
>> +#endif /* CONFIG_PPC_MPC512x */
>>  
>>  #ifdef CONFIG_FSL_SOC
>>  static const struct __devinitdata mpc_i2c_divider mpc_i2c_dividers_8xxx[] = {
>> @@ -322,12 +364,19 @@ static int __devinit mpc_i2c_get_fdr_8xxx(struct device_node *node, u32 clock,
>>  	return div ? (int)div->fdr : -EINVAL;
>>  }
>>  
>> -static void __devinit mpc_i2c_setclock_8xxx(struct device_node *node,
>> -					    struct mpc_i2c *i2c,
>> -					    u32 clock, u32 prescaler)
>> +static void __devinit mpc_i2c_setup_8xxx(struct device_node *node,
>> +					 struct mpc_i2c *i2c,
>> +					 u32 clock, u32 prescaler)
>>  {
>>  	int ret, fdr;
>>  
>> +	if (clock == -1) {
>> +		dev_dbg(i2c->dev, "using dfsrr %d, fdr %d\n",
>> +			readb(i2c->base + MPC_I2C_DFSRR),
>> +			readb(i2c->base + MPC_I2C_FDR));
>> +		return;	/* preserve clocking */
>> +	}
>> +
>>  	ret = mpc_i2c_get_fdr_8xxx(node, clock, prescaler);
>>  	fdr = (ret >= 0) ? ret : 0x1031; /* backward compatibility */
>>  
>> @@ -340,9 +389,9 @@ static void __devinit mpc_i2c_setclock_8xxx(struct device_node *node,
>>  }
>>  
>>  #else /* !CONFIG_FSL_SOC */
>> -static void __devinit mpc_i2c_setclock_8xxx(struct device_node *node,
>> -					    struct mpc_i2c *i2c,
>> -					    u32 clock, u32 prescaler)
>> +static void __devinit mpc_i2c_setup_8xxx(struct device_node *node,
>> +					 struct mpc_i2c *i2c,
>> +					 u32 clock, u32 prescaler)
>>  {
>>  }
>>  #endif /* CONFIG_FSL_SOC */
>> @@ -525,21 +574,21 @@ static int __devinit fsl_i2c_probe(struct of_device *op,
>>  		}
>>  	}
>>  
>> -	if (!of_get_property(op->node, "fsl,preserve-clocking", NULL)) {
>> +	if (of_get_property(op->node, "fsl,preserve-clocking", NULL)) {
>> +		clock = -1;
>> +	} else {
>>  		prop = of_get_property(op->node, "clock-frequency", &plen);
>>  		if (prop && plen == sizeof(u32))
>>  			clock = *prop;
>> +	}
>>  
>> -		if (match->data) {
>> -			struct mpc_i2c_data *data =
>> -				(struct mpc_i2c_data *)match->data;
>> -			data->setclock(op->node, i2c, clock, data->prescaler);
>> -		} else {
>> -			/* Backwards compatibility */
>> -			if (of_get_property(op->node, "dfsrr", NULL))
>> -				mpc_i2c_setclock_8xxx(op->node, i2c,
>> -						      clock, 0);
>> -		}
>> +	if (match->data) {
>> +		struct mpc_i2c_data *data = (struct mpc_i2c_data *)match->data;
> 
> The cast should not be necessary.

Right.

Wolfgang.