[PATCH 1/5] clk: ti: add custom API for memory access

[Dario Binacchi]

Hi Tero,

> Il 27/04/2021 09:01 Tero Kristo <kristo at kernel.org> ha scritto:
> 
>  
> Hi Dario,
> 
> One question below.
> 
> On 25/04/2021 17:17, Dario Binacchi wrote:
> > As pointed by [1] and [2], commit
> > d64b9cdcd4 ("fdt: translate address if #size-cells = <0>") is wrong:
> > - It makes every 'reg' DT property translatable. It changes the address
> >    translation so that for an I2C 'reg' address you'll get back as reg
> >    the I2C controller address + reg value.
> > - The quirk must be fixed with platform code.
> > 
> > The clk_ti_get_reg_addr() is the platform code able to make the correct
> > address translation for the AM33xx clocks registers. Its implementation
> > was inspired by the Linux Kernel code.
> > 
> > [1] https://patchwork.ozlabs.org/project/uboot/patch/1614324949-61314-1-git-send-email-bmeng.cn@gmail.com/
> > [2] https://lore.kernel.org/linux-clk/20210402192054.7934-1-dariobin@libero.it/T/
> > 
> > Signed-off-by: Dario Binacchi <dariobin at libero.it>
> > ---
> > 
> >   drivers/clk/ti/clk.c | 92 ++++++++++++++++++++++++++++++++++++++++++++
> >   drivers/clk/ti/clk.h | 13 +++++++
> >   2 files changed, 105 insertions(+)
> > 
> > diff --git a/drivers/clk/ti/clk.c b/drivers/clk/ti/clk.c
> > index c999df213a..68abe053cb 100644
> > --- a/drivers/clk/ti/clk.c
> > +++ b/drivers/clk/ti/clk.c
> > @@ -6,10 +6,23 @@
> >    */
> >   
> >   #include <common.h>
> > +#include <dm.h>
> >   #include <fdtdec.h>
> > +#include <regmap.h>
> >   #include <asm/io.h>
> > +#include <dm/device_compat.h>
> >   #include "clk.h"
> >   
> > +#define CLK_MAX_MEMMAPS           10
> > +
> > +struct clk_iomap {
> > +	struct regmap *regmap;
> > +	ofnode node;
> > +};
> > +
> > +static unsigned int clk_memmaps_num;
> > +static struct clk_iomap clk_memmaps[CLK_MAX_MEMMAPS];
> > +
> >   static void clk_ti_rmw(u32 val, u32 mask, fdt_addr_t reg)
> >   {
> >   	u32 v;
> > @@ -33,3 +46,82 @@ void clk_ti_latch(fdt_addr_t reg, s8 shift)
> >   	clk_ti_rmw(0, latch, reg);
> >   	readl(reg);		/* OCP barrier */
> >   }
> > +
> > +void clk_ti_writel(u32 val, struct clk_ti_reg *reg)
> > +{
> > +	struct clk_iomap *io = &clk_memmaps[reg->index];
> > +
> > +	regmap_write(io->regmap, reg->offset, val);
> > +}
> > +
> > +u32 clk_ti_readl(struct clk_ti_reg *reg)
> > +{
> > +	struct clk_iomap *io = &clk_memmaps[reg->index];
> > +	u32 val;
> > +
> > +	regmap_read(io->regmap, reg->offset, &val);
> > +	return val;
> > +}
> > +
> > +#if CONFIG_IS_ENABLED(AM33XX)
> 
> Why do you have this ifdef here? These drivers are not planned to be 
> used by anything but am33xx, or they don't work on any other device?
> 

The patch was developed and tested for the AM33XX SOC (beaglebone black). 
The drivers in the clk/ti folder were added by my patches but can also be
used by boards based on different device trees. In those cases, if required, 
platform versions of clk_ti_get_regmap_node() could be implemented.

Thanks and regards,
Dario

> -Tero
> 
> > +static ofnode clk_ti_get_regmap_node(struct udevice *dev)
> > +{
> > +	ofnode node = dev_ofnode(dev), parent;
> > +
> > +	if (!ofnode_valid(node))
> > +		return ofnode_null();
> > +
> > +	parent = ofnode_get_parent(node);
> > +	if (strcmp(ofnode_get_name(parent), "clocks"))
> > +		return ofnode_null();
> > +
> > +	return ofnode_get_parent(parent);
> > +}
> > +#else
> > +static ofnode clk_ti_get_regmap_node(struct udevice *dev)
> > +{
> > +	return ofnode_null();
> > +}
> > +#endif
> > +
> > +int clk_ti_get_reg_addr(struct udevice *dev, int index, struct clk_ti_reg *reg)
> > +{
> > +	ofnode node;
> > +	int i, ret;
> > +	u32 val;
> > +
> > +	ret = ofnode_read_u32_index(dev_ofnode(dev), "reg", index, &val);
> > +	if (ret) {
> > +		dev_err(dev, "%s must have reg[%d]\n", ofnode_get_name(node),
> > +			index);
> > +		return ret;
> > +	}
> > +
> > +	/* parent = ofnode_get_parent(parent); */
> > +	node = clk_ti_get_regmap_node(dev);
> > +	if (!ofnode_valid(node)) {
> > +		dev_err(dev, "failed to get regmap node\n");
> > +		return -EFAULT;
> > +	}
> > +
> > +	for (i = 0; i < clk_memmaps_num; i++) {
> > +		if (ofnode_equal(clk_memmaps[i].node, node))
> > +			break;
> > +	}
> > +
> > +	if (i == clk_memmaps_num) {
> > +		if (i == CLK_MAX_MEMMAPS)
> > +			return -ENOMEM;
> > +
> > +		ret = regmap_init_mem(node, &clk_memmaps[i].regmap);
> > +		if (ret)
> > +			return ret;
> > +
> > +		clk_memmaps[i].node = node;
> > +		clk_memmaps_num++;
> > +	}
> > +
> > +	reg->index = i;
> > +	reg->offset = val;
> > +	return 0;
> > +}
> > diff --git a/drivers/clk/ti/clk.h b/drivers/clk/ti/clk.h
> > index 601c3823f7..ea36d065ac 100644
> > --- a/drivers/clk/ti/clk.h
> > +++ b/drivers/clk/ti/clk.h
> > @@ -9,5 +9,18 @@
> >   #define _CLK_TI_H
> >   
> >   void clk_ti_latch(fdt_addr_t reg, s8 shift);
> > +/**
> > + * struct clk_ti_reg - TI register declaration
> > + * @offset: offset from the master IP module base address
> > + * @index: index of the master IP module
> > + */
> > +struct clk_ti_reg {
> > +	u16 offset;
> > +	u8 index;
> > +};
> > +
> > +void clk_ti_writel(u32 val, struct clk_ti_reg *reg);
> > +u32 clk_ti_readl(struct clk_ti_reg *reg);
> > +int clk_ti_get_reg_addr(struct udevice *dev, int index, struct clk_ti_reg *reg);
> >   
> >   #endif /* #ifndef _CLK_TI_H */
> >