[PATCH v2 07/12] at91: dt: smc: Added smc bus driver

Jean-Jacques Hiblot jjhiblot at traphandler.com
Fri Jan 10 06:01:47 EST 2014


2014/1/9 Jean-Jacques Hiblot <jjhiblot at traphandler.com>:
> Hi Boris,
>
> 2014/1/9 boris brezillon <b.brezillon at overkiz.com>:
>> Hello JJ,
>>
>>
>> On 09/01/2014 13:31, Jean-Jacques Hiblot wrote:
>>>
>>> The EBI/SMC external interface is used to access external peripherals
>>> (NAND
>>> and Ethernet controller in the case of sam9261ek). Different
>>> configurations and
>>> timings are required for those peripherals. This bus driver can be used to
>>> setup the bus timings/configuration from the device tree.
>>> It currently accepts timings in clock period and in nanoseconds.
>>>
>>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot at traphandler.com>
>>> ---
>>>   drivers/memory/Kconfig     |  10 ++
>>>   drivers/memory/Makefile    |   1 +
>>>   drivers/memory/atmel-smc.c | 431
>>> +++++++++++++++++++++++++++++++++++++++++++++
>>>   3 files changed, 442 insertions(+)
>>>   create mode 100644 drivers/memory/atmel-smc.c
>>>
>>> diff --git a/drivers/memory/Kconfig b/drivers/memory/Kconfig
>>> index 29a11db..fbdfd63 100644
>>> --- a/drivers/memory/Kconfig
>>> +++ b/drivers/memory/Kconfig
>>> @@ -50,4 +50,14 @@ config TEGRA30_MC
>>>           analysis, especially for IOMMU/SMMU(System Memory Management
>>>           Unit) module.
>>>   +config ATMEL_SMC
>>> +       bool "Atmel SMC/EBI driver"
>>> +       default y
>>> +       depends on SOC_AT91SAM9 && OF
>>> +       help
>>> +         Driver for Atmel SMC/EBI controller.
>>> +         Used to configure the EBI (external bus interface) when the
>>> device-
>>> +         tree is used. This bus supports NANDs, external ethernet
>>> controller,
>>> +         SRAMs, ATA devices, etc.
>>> +
>>>   endif
>>> diff --git a/drivers/memory/Makefile b/drivers/memory/Makefile
>>> index 969d923..101abc4 100644
>>> --- a/drivers/memory/Makefile
>>> +++ b/drivers/memory/Makefile
>>> @@ -9,3 +9,4 @@ obj-$(CONFIG_TI_EMIF)           += emif.o
>>>   obj-$(CONFIG_MVEBU_DEVBUS)    += mvebu-devbus.o
>>>   obj-$(CONFIG_TEGRA20_MC)      += tegra20-mc.o
>>>   obj-$(CONFIG_TEGRA30_MC)      += tegra30-mc.o
>>> +obj-$(CONFIG_ATMEL_SMC)        += atmel-smc.o
>>> diff --git a/drivers/memory/atmel-smc.c b/drivers/memory/atmel-smc.c
>>> new file mode 100644
>>> index 0000000..0a1d9ba
>>> --- /dev/null
>>> +++ b/drivers/memory/atmel-smc.c
>>> @@ -0,0 +1,431 @@
>>> +/*
>>> + * EBI driver for Atmel SAM9 chips
>>> + * inspired by the fsl weim bus driver
>>> + *
>>> + * Copyright (C) 2013 JJ Hiblot.
>>> + *
>>> + * This file is licensed under the terms of the GNU General Public
>>> + * License version 2. This program is licensed "as is" without any
>>> + * warranty of any kind, whether express or implied.
>>> + */
>>> +#include <linux/module.h>
>>> +#include <linux/clk.h>
>>> +#include <linux/io.h>
>>> +#include <linux/of_device.h>
>>> +#include <mach/at91sam9_smc.h>
>>
>>
>> You should avoid machine specific headers inclusions: we're trying to get
>> rid of them.
>>
>> Duplicate the code and macros you need in your driver instead.
>
> Is this the right way? We usually try to avoid duplication.
>
>>
>>
>>> +
>>> +struct  smc_data {
>>> +       struct clk *bus_clk;
>>> +       void __iomem *base;
>>> +       struct device *dev;
>>> +};
>>> +
>>> +struct at91_smc_devtype {
>>> +       unsigned int    cs_count;
>>> +};
>>> +
>>> +static const struct at91_smc_devtype sam9261_smc_devtype = {
>>> +       .cs_count       = 6,
>>> +};
>>> +
>>> +static const struct of_device_id smc_id_table[] = {
>>> +       { .compatible = "atmel,at91sam9261-smc", .data =
>>> &sam9261_smc_devtype},
>>> +       { }
>>> +};
>>> +MODULE_DEVICE_TABLE(of, smc_id_table);
>>> +
>>> +struct smc_parameters_type {
>>> +       const char *name;
>>> +       u16 width;
>>> +       u16 shift;
>>> +};
>>> +
>>> +static const struct smc_parameters_type smc_parameters[] = {
>>> +       {"smc,burst_size",      2, 28},
>>> +       {"smc,burst_enabled",   1, 24},
>>> +       {"smc,tdf_mode",        1, 20},
>>> +       {"smc,bus_width",       2, 12},
>>> +       {"smc,byte_access_type", 1,  8},
>>> +       {"smc,nwait_mode",      2,  4},
>>> +       {"smc,write_mode",      1,  0},
>>> +       {"smc,read_mode",       1,  1},
>>> +       {NULL}
>>> +};
>>> +
>>> +static int get_mode_register_from_dt(struct smc_data *smc,
>>> +                                    struct device_node *np,
>>> +                                    struct sam9_smc_config *cfg)
>>> +{
>>> +       int ret;
>>> +       u32 val;
>>> +       struct device *dev = smc->dev;
>>> +       const struct smc_parameters_type *p = smc_parameters;
>>> +       u32 mode = cfg->mode;
>>> +
>>> +       while (p->name) {
>>> +               ret = of_property_read_u32(np, p->name , &val);
>>> +               if (ret == -EINVAL) {
>>> +                       dev_dbg(dev, "%s: property %s not set.\n",
>>> np->name,
>>> +                               p->name);
>>> +                       p++;
>>> +                       continue;
>>> +               } else if (ret) {
>>> +                       dev_err(dev, "%s: can't get property %s.\n",
>>> np->name,
>>> +                               p->name);
>>> +                       return ret;
>>> +               }
>>> +               if (val >= (1<<p->width)) {
>>> +                       dev_err(dev, "%s: property %s out of range.\n",
>>> +                               np->name, p->name);
>>> +                       return -ERANGE;
>>> +               }
>>> +               mode &= ~(((1<<p->width)-1) << p->shift);
>>> +               mode |= (val << p->shift);
>>> +               p++;
>>> +       }
>>> +       cfg->mode = mode;
>>> +       return 0;
>>> +}
>>> +
>>> +static int generic_timing_from_dt(struct smc_data *smc, struct
>>> device_node *np,
>>> +                                 struct sam9_smc_config *cfg)
>>> +{
>>> +       u32 val;
>>> +
>>> +       if (!of_property_read_u32(np, "smc,ncs_read_setup" , &val))
>>> +               cfg->ncs_read_setup = val;
>>> +
>>> +       if (!of_property_read_u32(np, "smc,nrd_setup" , &val))
>>> +               cfg->nrd_setup = val;
>>> +
>>> +       if (!of_property_read_u32(np, "smc,ncs_write_setup" , &val))
>>> +               cfg->ncs_write_setup = val;
>>> +
>>> +       if (!of_property_read_u32(np, "smc,nwe_setup" , &val))
>>> +               cfg->nwe_setup = val;
>>> +
>>> +       if (!of_property_read_u32(np, "smc,ncs_read_pulse" , &val))
>>> +               cfg->ncs_read_pulse = val;
>>> +
>>> +       if (!of_property_read_u32(np, "smc,nrd_pulse" , &val))
>>> +               cfg->nrd_pulse = val;
>>> +
>>> +       if (!of_property_read_u32(np, "smc,ncs_write_pulse" , &val))
>>> +               cfg->ncs_write_pulse = val;
>>> +
>>> +       if (!of_property_read_u32(np, "smc,nwe_pulse" , &val))
>>> +               cfg->nwe_pulse = val;
>>> +
>>> +       if (!of_property_read_u32(np, "smc,read_cycle" , &val))
>>> +               cfg->read_cycle = val;
>>> +
>>> +       if (!of_property_read_u32(np, "smc,write_cycle" , &val))
>>> +               cfg->write_cycle = val;
>>> +
>>> +       if (!of_property_read_u32(np, "smc,tdf_cycles" , &val))
>>> +               cfg->tdf_cycles = val;
>>> +
>>> +       return get_mode_register_from_dt(smc, np, cfg);
>>> +}
>>> +
>>> +/* convert the time in ns in a number of clock cycles */
>>> +static u32 ns_to_cycles(u32 ns, u32 clk)
>>> +{
>>> +       /*
>>> +        * convert the clk to kHz for the rest of the calculation to avoid
>>> +        * overflow
>>> +        */
>>> +       u32 clk_kHz = clk / 1000;
>>> +       u32 ncycles = ((ns * clk_kHz) + 1000000 - 1) / 1000000;
>>
>> What about using an u64 type and do_div ?
>
> easier and faster (though it's not the point here) this way, and kHz
> ist not so imprecise :-)
>
>>
>>> +       return ncycles;
>>> +}
>>> +
>>> +static u32 cycles_to_coded_cycle(u32 cycles, int a, int b)
>>> +{
>>> +       u32 mask_high = (1 << a) - 1;
>>> +       u32 mask_low = (1 << b) - 1;
>>> +       u32 coded;
>>> +
>>> +       /* check if the value can be described with the coded format */
>>> +       if (cycles & (mask_high & ~mask_low)) {
>>> +               /* not representable. we need to round up */
>>> +               cycles |= mask_high;
>>> +               cycles += 1;
>>> +       }
>>> +       /* Now the value can be represented in the coded format */
>>> +       coded = (cycles & ~mask_high) >> (a - b);
>>> +       coded |= (cycles & mask_low);
>>> +       return coded;
>>> +}
>>> +
>>> +static u32 ns_to_rw_cycles(u32 ns, u32 clk)
>>> +{
>>> +       return cycles_to_coded_cycle(ns_to_cycles(ns, clk), 8, 7);
>>> +}
>>> +
>>> +static u32 ns_to_pulse_cycles(u32 ns, u32 clk)
>>> +{
>>> +       return cycles_to_coded_cycle(ns_to_cycles(ns, clk), 8, 6);
>>> +}
>>> +
>>> +static u32 ns_to_setup_cycles(u32 ns, u32 clk)
>>> +{
>>> +       return cycles_to_coded_cycle(ns_to_cycles(ns, clk), 7, 5);
>>> +}
>>> +
>>> +static u32 cycles_to_ns(u32 cycles, u32 clk)
>>> +{
>>> +       /*
>>> +        * convert the clk to kHz for the rest of the calculation to avoid
>>> +        * overflow
>>> +        */
>>> +       u32 clk_kHz = clk / 1000;
>>
>>
>> Ditto (u64 + do_div).
>>
>>> +       return (cycles * 1000000) / clk_kHz;
>>> +}
>>> +
>>> +static u32 coded_cycle_to_cycles(u32 coded, int a, int b)
>>> +{
>>> +       u32 cycles = (coded >> b) << a;
>>> +       u32 mask_low = (1 << b) - 1;
>>> +       cycles |= (coded & mask_low);
>>> +       return cycles;
>>> +}
>>> +
>>> +static u32 rw_cycles_to_ns(u32 reg, u32 clk)
>>> +{
>>> +       return cycles_to_ns(coded_cycle_to_cycles(reg, 8, 7), clk);
>>> +}
>>> +
>>> +static u32 pulse_cycles_to_ns(u32 reg, u32 clk)
>>> +{
>>> +       return cycles_to_ns(coded_cycle_to_cycles(reg, 8, 6), clk);
>>> +}
>>> +
>>> +static u32 setup_cycles_to_ns(u32 reg, u32 clk)
>>> +{
>>> +       return cycles_to_ns(coded_cycle_to_cycles(reg, 7, 5), clk);
>>> +}
>>> +
>>> +static void dump_timing(struct smc_data *smc, struct sam9_smc_config
>>> *config)
>>> +{
>>> +       u32 freq = clk_get_rate(smc->bus_clk);
>>> +       struct device *dev = smc->dev;
>>> +
>>> +#define DUMP(fn, y)    dev_info(dev, "%s : 0x%x (%d ns)\n", #y,
>>> config->y,\
>>> +                                fn(config->y, freq))
>>> +#define DUMP_PULSE(y)  DUMP(pulse_cycles_to_ns, y)
>>> +#define DUMP_RWCYCLE(y)        DUMP(rw_cycles_to_ns, y)
>>> +#define DUMP_SETUP(y)  DUMP(setup_cycles_to_ns, y)
>>> +#define DUMP_SIMPLE(y) DUMP(cycles_to_ns, y)
>>> +
>>> +       DUMP_SETUP(nwe_setup);
>>> +       DUMP_SETUP(ncs_write_setup);
>>> +       DUMP_SETUP(nrd_setup);
>>> +       DUMP_SETUP(ncs_read_setup);
>>> +       DUMP_PULSE(nwe_pulse);
>>> +       DUMP_PULSE(ncs_write_pulse);
>>> +       DUMP_PULSE(nrd_pulse);
>>> +       DUMP_PULSE(ncs_read_pulse);
>>> +       DUMP_RWCYCLE(write_cycle);
>>> +       DUMP_RWCYCLE(read_cycle);
>>> +       DUMP_SIMPLE(tdf_cycles);
>>> +}
>>> +
>>> +static int ns_timing_from_dt(struct smc_data *smc, struct device_node
>>> *np,
>>> +                            struct sam9_smc_config *cfg)
>>> +{
>>> +       u32 t_ns;
>>> +       u32 freq = clk_get_rate(smc->bus_clk);
>>> +
>>> +       if (!of_property_read_u32(np, "smc,ncs_read_setup" , &t_ns))
>>> +               cfg->ncs_read_setup = ns_to_setup_cycles(t_ns, freq);
>>> +
>>> +       if (!of_property_read_u32(np, "smc,nrd_setup" , &t_ns))
>>> +               cfg->nrd_setup = ns_to_setup_cycles(t_ns, freq);
>>> +
>>> +       if (!of_property_read_u32(np, "smc,ncs_write_setup" , &t_ns))
>>> +               cfg->ncs_write_setup = ns_to_setup_cycles(t_ns, freq);
>>> +
>>> +       if (!of_property_read_u32(np, "smc,nwe_setup" , &t_ns))
>>> +               cfg->nwe_setup = ns_to_setup_cycles(t_ns, freq);
>>> +
>>> +       if (!of_property_read_u32(np, "smc,ncs_read_pulse" , &t_ns))
>>> +               cfg->ncs_read_pulse = ns_to_pulse_cycles(t_ns, freq);
>>> +
>>> +       if (!of_property_read_u32(np, "smc,nrd_pulse" , &t_ns))
>>> +               cfg->nrd_pulse = ns_to_pulse_cycles(t_ns, freq);
>>> +
>>> +       if (!of_property_read_u32(np, "smc,ncs_write_pulse" , &t_ns))
>>> +               cfg->ncs_write_pulse = ns_to_pulse_cycles(t_ns, freq);
>>> +
>>> +       if (!of_property_read_u32(np, "smc,nwe_pulse" , &t_ns))
>>> +               cfg->nwe_pulse = ns_to_pulse_cycles(t_ns, freq);
>>> +
>>> +       if (!of_property_read_u32(np, "smc,read_cycle" , &t_ns))
>>> +               cfg->read_cycle = ns_to_rw_cycles(t_ns, freq);
>>> +
>>> +       if (!of_property_read_u32(np, "smc,write_cycle" , &t_ns))
>>> +               cfg->write_cycle = ns_to_rw_cycles(t_ns, freq);
>>> +
>>> +       if (!of_property_read_u32(np, "smc,tdf_cycles" , &t_ns))
>>> +               cfg->tdf_cycles = ns_to_cycles(t_ns, freq);
>>> +
>>> +       return get_mode_register_from_dt(smc, np, cfg);
>>> +}
>>> +
>>> +struct converter {
>>> +       const char *name;
>>> +       int (*fn) (struct smc_data *smc, struct device_node *np,
>>> +                  struct sam9_smc_config *cfg);
>>> +};
>>> +static const struct converter converters[] = {
>>> +       {"raw", generic_timing_from_dt},
>>> +       {"nanosec", ns_timing_from_dt},
>>> +};
>>
>>
>> Could you use more specific names like:
>> "atmel,smc-converter-generic"
>> "atmel,smc-converter-nand"
>> ...
> Isn't it a bit redudant? smc,converter = "atmel,smc-converter-generic";
>
>>
>> IMHO the timing unit should be specified in the property names:
>> smc,ncs_read_setup-ns
>> smc,ncs_read_setup-cycles
>>
> True. Although cycles is misleading. It's more a raw register value.
> For pulse, setup and rw cycle, the register value is not identical to
> the number of cycles.
>>
>>
>>
>>> +
>>> +/* Parse and set the timing for this device. */
>>> +static int smc_timing_setup(struct smc_data *smc, struct device_node *np,
>>> +               const struct at91_smc_devtype *devtype)
>>> +{
>>> +       int ret;
>>> +       u32 cs;
>>> +       int i;
>>> +       struct device *dev = smc->dev;
>>> +       const struct converter *converter;
>>> +       const char *converter_name = NULL;
>>> +       struct sam9_smc_config cfg;
>>> +
>>> +       ret = of_property_read_u32(np, "smc,cs" , &cs);
>>
>>
>> Shouldn't this be stored in the reg property ?
>> After all, in your DM9000 patch you use "@cs,offset" to identify the node...
> True
I gave this more thoughts and don't think it should be in a reg
property. We already have the cs information in the address
translation. So maybe the CS should extr

>
>>
>>
>>> +       if (ret < 0) {
>>> +               dev_err(dev, "missing mandatory property : smc,cs\n");
>>> +               return ret;
>>> +       }
>>> +       if (cs >= devtype->cs_count) {
>>> +               dev_err(dev, "invalid value for property smc,cs (=%d)."
>>> +               "Must be in range 0 to %d\n", cs, devtype->cs_count-1);
>>> +               return -EINVAL;
>>> +       }
>>> +
>>> +       of_property_read_string(np, "smc,converter", &converter_name);
>>
>>
>> What about using the "compatible" property + struct of_device_id instead of
>> "smc,converter" property + struct converter ?
>
> Because one instance of the driver handles several chip selects and
> each may use a different converter.
>
>>
>>
>>> +       if (converter_name) {
>>> +               for (i = 0; i < ARRAY_SIZE(converters); i++)
>>> +                       if (strcmp(converters[i].name, converter_name) ==
>>> 0)
>>> +                               converter = &converters[i];
>>> +               if (!converter) {
>>> +                       dev_info(dev, "unknown converter. aborting\n");
>>> +                       return -EINVAL;
>>> +               }
>>> +       } else {
>>> +               dev_dbg(dev, "cs %d: no smc converter provided. using "
>>> +               "raw register values\n", cs);
>>> +               converter = &converters[0];
>>> +       }
>>> +       dev_dbg(dev, "cs %d using converter : %s\n", cs, converter->name);
>>> +       sam9_smc_cs_read(smc->base + (0x10 * cs), &cfg);
>>> +       converter->fn(smc, np, &cfg);
>>> +       ret = sam9_smc_check_cs_configuration(&cfg);
>>> +       if (ret < 0) {
>>> +               dev_info(dev, "invalid smc configuration for cs %d."
>>> +               "clipping values\n", cs);
>>> +               sam9_smc_clip_cs_configuration(&cfg);
>>> +               dump_timing(smc, &cfg);
>>> +       }
>>> +#ifdef DEBUG
>>> +       else
>>> +               dump_timing(smc, &cfg);
>>> +#endif
>>
>>
>> I'm not a big fan of #ifdef blocks inside the code.
>> You could define a dummy dump_timing function if DEBUG is not defined:
>>
>> #ifdef DEBUG
>>
>>
>> static void dump_timing(struct smc_data *smc, struct sam9_smc_config
>> *config)
>> {
>>     /* your implementation */
>> }
>>
>> #else
>>
>> static inline void dump_timing(struct smc_data *smc, struct sam9_smc_config
>> *config)
>> {
>> }
>>
>> #endif
>>
>> Or just use dev_dbg when printing things in dump_timing.
>>
> I wanted to know the values when they were modified (clipped) by the
> driver. But it could be removed, knowing that clipping occurred is
> enough.
>>
>>
>>> +
>>> +       sam9_smc_cs_configure(smc->base + (0x10 * cs), &cfg);
>>> +       return 0;
>>> +}
>>> +
>>> +static int smc_parse_dt(struct smc_data *smc)
>>> +{
>>> +       struct device *dev = smc->dev;
>>> +       const struct of_device_id *of_id = of_match_device(smc_id_table,
>>> dev);
>>> +       const struct at91_smc_devtype *devtype = of_id->data;
>>> +       struct device_node *child;
>>> +       int ret;
>>> +
>>> +       for_each_child_of_node(dev->of_node, child) {
>>> +               if (!child->name)
>>> +                       continue;
>>> +               if (!of_device_is_available(child))
>>> +                       continue;
>>> +               ret = smc_timing_setup(smc, child, devtype);
>>> +               if (ret) {
>>> +                       static struct property status = {
>>> +                               .name = "status",
>>> +                               .value = "disabled",
>>> +                               .length = sizeof("disabled"),
>>> +                       };
>>> +                       dev_err(dev, "%s set timing failed. This node will
>>> be disabled.\n",
>>> +                               child->full_name);
>>> +                       ret = of_update_property(child, &status);
>>> +                       if (ret < 0) {
>>> +                               dev_err(dev, "can't disable %s. aborting
>>> probe\n",
>>> +                               child->full_name);
>>> +                               break;
>>
>>
>> The concept of disabling the device if timings cannot be met sounds
>> interresting...
>> Let's see what other maintainers say about this :).
>>
>>
>>> +                       }
>>> +               }
>>> +       }
>>> +
>>> +       ret = of_platform_populate(dev->of_node,
>>> of_default_bus_match_table,
>>> +                                  NULL, dev);
>>> +       if (ret)
>>> +               dev_err(dev, "%s fail to create devices.\n",
>>> +                       dev->of_node->full_name);
>>> +
>>> +       return ret;
>>> +}
>>> +
>>> +static int smc_probe(struct platform_device *pdev)
>>> +{
>>> +       struct resource *res;
>>> +       int ret;
>>> +       void __iomem *base;
>>> +       struct clk *clk;
>>> +       struct smc_data *smc = devm_kzalloc(&pdev->dev, sizeof(struct
>>> smc_data),
>>> +                                           GFP_KERNEL);
>>> +
>>> +       if (!smc)
>>> +               return -ENOMEM;
>>> +
>>> +       smc->dev = &pdev->dev;
>>> +
>>> +       /* get the resource */
>>> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>> +       base = devm_request_and_ioremap(&pdev->dev, res);
>>> +       if (IS_ERR(base)) {
>>> +               dev_err(&pdev->dev, "can't map SMC base address\n");
>>> +               return PTR_ERR(base);
>>> +       }
>>> +
>>> +       /* get the clock */
>>> +       clk = devm_clk_get(&pdev->dev, "smc");
>>> +       if (IS_ERR(clk))
>>> +               return PTR_ERR(clk);
>>> +
>>> +       smc->bus_clk = clk;
>>> +       smc->base = base;
>>> +
>>> +       /* parse the device node */
>>> +       ret = smc_parse_dt(smc);
>>> +       if (!ret)
>>> +               dev_info(&pdev->dev, "Driver registered.\n");
>>> +
>>> +       return ret;
>>> +}
>>> +
>>> +static struct platform_driver smc_driver = {
>>> +       .driver = {
>>> +               .name           = "atmel-smc",
>>> +               .owner          = THIS_MODULE,
>>> +               .of_match_table = smc_id_table,
>>> +       },
>>> +};
>>> +module_platform_driver_probe(smc_driver, smc_probe);
>>> +
>>> +MODULE_AUTHOR("JJ Hiblot");
>>> +MODULE_DESCRIPTION("Atmel's SMC/EBI driver");
>>> +MODULE_LICENSE("GPL");
>>
>>
>>
>> That's all for now. :)
>>
>> I'll try to test it this week end on a sama5 board.
>
> Thanks
>
>>
>> Best Regards,
>>
>> Boris



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