Re: [PATCH v2 4/4] clk: mediatek: Add USB clock support in MT8173 APMIXEDSYS

From: Daniel Kurtz
Date: Wed Jul 01 2015 - 11:23:07 EST

Hi James,

This looks like 3 separate gate clocks in a chain, with a timing
constraint: USB_LPF must be enabled 100 us after USB_TX.

26MHz--> [GATE] --USB_TX--> [LPF] --USB_LPF--> [GATE] --USB_OUT-->
^ ^ ^
+--------------+ | |
AP_PLL_CON2.REF2USB_TX_EN -+ | |
AP_PLL_CON2.REF2USB_TX_LPF_EN -+ |
AP_PLL_CON2.REF2USB_TX_OUT_EN --------------------+


I think we can model the gate parts using a proper clock tree model
and the existing clock gate semantics.
I'm not sure the best way to model the delay; but in theory that could
be handled by the clock user (USB driver).

-Dan

On Wed, Jul 1, 2015 at 11:22 PM, Daniel Kurtz <djkurtz@xxxxxxxxxxxx> wrote:
> Hi James,
>
> This looks like 3 separate gate clocks in a chain, with a timing constraint:
> USB_LPF must be enabled 100 us after USB_TX.
>
> 26MHz--> [GATE] --USB_TX--> [LPF] --USB_LPF--> [GATE] --USB_OUT-->
> ^ ^ ^
> +--------------+ | |
> AP_PLL_CON2.REF2USB_TX_EN -+ | |
> AP_PLL_CON2.REF2USB_TX_LPF_EN -+ |
> AP_PLL_CON2.REF2USB_TX_OUT_EN --------------------+
>
>
> I think we can model the gate parts using a proper clock tree model and the
> existing clock gate semantics.
> I'm not sure the best way to model the delay; but in theory that could be
> handled by the clock user (USB driver).
>
> -Dan
>
> On Tue, Jun 30, 2015 at 10:58 AM, James Liao <jamesjj.liao@xxxxxxxxxxxx>
> wrote:
>> Add REF2USB_TX clock support into MT8173 APMIXEDSYS. This clock
>> is needed by USB 3.0.
>>
>> Signed-off-by: James Liao <jamesjj.liao@xxxxxxxxxxxx>
>> ---
>> drivers/clk/mediatek/clk-mt8173.c | 143
>> +++++++++++++++++++++++++++++++++
>> drivers/clk/mediatek/clk-pll.c | 7 +-
>> include/dt-bindings/clock/mt8173-clk.h | 3 +-
>> 3 files changed, 146 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/clk/mediatek/clk-mt8173.c
>> b/drivers/clk/mediatek/clk-mt8173.c
>> index 75be757..333b6af 100644
>> --- a/drivers/clk/mediatek/clk-mt8173.c
>> +++ b/drivers/clk/mediatek/clk-mt8173.c
>> @@ -12,6 +12,7 @@
>> * GNU General Public License for more details.
>> */
>>
>> +#include <linux/delay.h>
>> #include <linux/of.h>
>> #include <linux/of_address.h>
>> #include <linux/slab.h>
>> @@ -968,6 +969,141 @@ static void __init mtk_pericfg_init(struct
>> device_node *node)
>> }
>> CLK_OF_DECLARE(mtk_pericfg, "mediatek,mt8173-pericfg", mtk_pericfg_init);
>>
>> +#define REF2USB_TX_EN BIT(0)
>> +#define REF2USB_TX_LPF_EN BIT(1)
>> +#define REF2USB_TX_OUT_EN BIT(2)
>> +#define REF2USB_EN_MASK (REF2USB_TX_EN | REF2USB_TX_LPF_EN
>> | \
>> + REF2USB_TX_OUT_EN)
>> +
>> +struct mtk_ref2usb_tx {
>> + struct clk_hw hw;
>> + void __iomem *base_addr;
>> +};
>> +
>> +static inline struct mtk_ref2usb_tx *to_mtk_ref2usb_tx(struct clk_hw *hw)
>> +{
>> + return container_of(hw, struct mtk_ref2usb_tx, hw);
>> +}
>> +
>> +static int mtk_ref2usb_tx_is_prepared(struct clk_hw *hw)
>> +{
>> + struct mtk_ref2usb_tx *tx = to_mtk_ref2usb_tx(hw);
>> +
>> + return (readl(tx->base_addr) & REF2USB_EN_MASK) ==
>> REF2USB_EN_MASK;
>> +}
>> +
>> +static int mtk_ref2usb_tx_prepare(struct clk_hw *hw)
>> +{
>> + struct mtk_ref2usb_tx *tx = to_mtk_ref2usb_tx(hw);
>> + u32 val;
>> +
>> + val = readl(tx->base_addr);
>> +
>> + val |= REF2USB_TX_EN;
>> + writel(val, tx->base_addr);
>> + udelay(100);
>> +
>> + val |= REF2USB_TX_LPF_EN;
>> + writel(val, tx->base_addr);
>> +
>> + val |= REF2USB_TX_OUT_EN;
>> + writel(val, tx->base_addr);
>> +
>> + return 0;
>> +}
>> +
>> +static void mtk_ref2usb_tx_unprepare(struct clk_hw *hw)
>> +{
>> + struct mtk_ref2usb_tx *tx = to_mtk_ref2usb_tx(hw);
>> + u32 val;
>> +
>> + val = readl(tx->base_addr);
>> + val &= ~REF2USB_EN_MASK;
>> + writel(val, tx->base_addr);
>> +}
>> +
>> +static const struct clk_ops mtk_ref2usb_tx_ops = {
>> + .is_prepared = mtk_ref2usb_tx_is_prepared,
>> + .prepare = mtk_ref2usb_tx_prepare,
>> + .unprepare = mtk_ref2usb_tx_unprepare,
>> +};
>> +
>> +static struct clk *mtk_clk_register_ref2usb_tx(const char *name,
>> + const char *parent_name, void __iomem *reg)
>> +{
>> + struct mtk_ref2usb_tx *tx;
>> + struct clk_init_data init = {};
>> + struct clk *clk;
>> +
>> + tx = kzalloc(sizeof(*tx), GFP_KERNEL);
>> + if (!tx)
>> + return ERR_PTR(-ENOMEM);
>> +
>> + tx->base_addr = reg;
>> + tx->hw.init = &init;
>> +
>> + init.name = name;
>> + init.ops = &mtk_ref2usb_tx_ops;
>> + init.parent_names = &parent_name;
>> + init.num_parents = 1;
>> +
>> + clk = clk_register(NULL, &tx->hw);
>> +
>> + if (IS_ERR(clk)) {
>> + pr_err("Failed to register clk %s: %ld\n", name,
>> PTR_ERR(clk));
>> + kfree(tx);
>> + }
>> +
>> + return clk;
>> +}
>> +
>> +struct mtk_apmixed_ex {
>> + int id;
>> + const char *name;
>> + const char *parent;
>> + u32 reg_ofs;
>> +};
>> +
>> +#define APMIXED_EX(_id, _name, _parent, _reg_ofs) { \
>> + .id = _id, \
>> + .name = _name, \
>> + .parent = _parent, \
>> + .reg_ofs = _reg_ofs, \
>> + }
>> +
>> +static const struct mtk_apmixed_ex apmixed_ex[] = {
>> + APMIXED_EX(CLK_APMIXED_REF2USB_TX, "ref2usb_tx", "clk26m", 0x8),
>> +};
>> +
>> +static void __init mtk_clk_register_apmixedsys_special(struct device_node
>> *node,
>> + struct clk_onecell_data *clk_data)
>> +{
>> + void __iomem *base;
>> + struct clk *clk;
>> + int i;
>> +
>> + base = of_iomap(node, 0);
>> + if (!base) {
>> + pr_err("%s(): ioremap failed\n", __func__);
>> + return;
>> + }
>> +
>> + for (i = 0; i < ARRAY_SIZE(apmixed_ex); i++) {
>> + const struct mtk_apmixed_ex *ape = &apmixed_ex[i];
>> +
>> + clk = mtk_clk_register_ref2usb_tx(ape->name, ape->parent,
>> + base +
>> ape->reg_ofs);
>> +
>> + if (IS_ERR(clk)) {
>> + pr_err("Failed to register clk %s: %ld\n",
>> ape->name,
>> + PTR_ERR(clk));
>> + continue;
>> + }
>> +
>> + clk_data->clks[CLK_APMIXED_REF2USB_TX] = clk;
>> + }
>> +}
>> +
>> #define MT8173_PLL_FMAX (3000UL * MHZ)
>>
>> #define CON0_MT8173_RST_BAR BIT(24)
>> @@ -1010,12 +1146,19 @@ static const struct mtk_pll_data plls[] = {
>> static void __init mtk_apmixedsys_init(struct device_node *node)
>> {
>> struct clk_onecell_data *clk_data;
>> + int r;
>>
>> mt8173_pll_clk_data = clk_data =
>> mtk_alloc_clk_data(CLK_APMIXED_NR_CLK);
>> if (!clk_data)
>> return;
>>
>> mtk_clk_register_plls(node, plls, ARRAY_SIZE(plls), clk_data);
>> + mtk_clk_register_apmixedsys_special(node, clk_data);
>> +
>> + r = of_clk_add_provider(node, of_clk_src_onecell_get, clk_data);
>> + if (r)
>> + pr_err("%s(): could not register clock provider: %d\n",
>> + __func__, r);
>>
>> mtk_clk_enable_critical();
>> }
>> diff --git a/drivers/clk/mediatek/clk-pll.c
>> b/drivers/clk/mediatek/clk-pll.c
>> index 44409e9..813f0c7 100644
>> --- a/drivers/clk/mediatek/clk-pll.c
>> +++ b/drivers/clk/mediatek/clk-pll.c
>> @@ -302,7 +302,7 @@ void __init mtk_clk_register_plls(struct device_node
>> *node,
>> const struct mtk_pll_data *plls, int num_plls, struct
>> clk_onecell_data *clk_data)
>> {
>> void __iomem *base;
>> - int r, i;
>> + int i;
>> struct clk *clk;
>>
>> base = of_iomap(node, 0);
>> @@ -324,9 +324,4 @@ void __init mtk_clk_register_plls(struct device_node
>> *node,
>>
>> clk_data->clks[pll->id] = clk;
>> }
>> -
>> - r = of_clk_add_provider(node, of_clk_src_onecell_get, clk_data);
>> - if (r)
>> - pr_err("%s(): could not register clock provider: %d\n",
>> - __func__, r);
>> }
>> diff --git a/include/dt-bindings/clock/mt8173-clk.h
>> b/include/dt-bindings/clock/mt8173-clk.h
>> index 6ce88bf..7b7c555 100644
>> --- a/include/dt-bindings/clock/mt8173-clk.h
>> +++ b/include/dt-bindings/clock/mt8173-clk.h
>> @@ -172,7 +172,8 @@
>> #define CLK_APMIXED_APLL2 12
>> #define CLK_APMIXED_LVDSPLL 13
>> #define CLK_APMIXED_MSDCPLL2 14
>> -#define CLK_APMIXED_NR_CLK 15
>> +#define CLK_APMIXED_REF2USB_TX 15
>> +#define CLK_APMIXED_NR_CLK 16
>>
>> /* INFRA_SYS */
>>
>> --
>> 1.8.1.1.dirty
>>
>
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