While testing the dwmac-meson8b with an RGMII PHY on Meson8b we
discovered that the m25_div is not actually a divider but rather a gate.
This matches with the datasheet which describes bit 10 as "Generate
25MHz clock for PHY". Back when the driver was written it was assumed
that this was a divider (which could divide by 5 or 10) because other
clock bits in the datasheet were documented incorrectly.
Tests have shown that without bit 10 set the RTL8211F RGMII PHY on
Odroid-C1 (using a Meson8b SoC) does not work.
On GXBB and newer SoCs (where the driver was initially tested with RGMII
PHYs) this is not a problem because the input clock is running at 1GHz.
The m250_div clock's biggest possible divider is 7 (3-bit divider, with
value 0 being reserved). Thus we end up with a m250_div of 4 and a
"m25_div" of 10 (= register value 1).
Instead it turns out that the Ethernet IP block seems to have a fixed
"divide by 10" clock internally. This means that bit 10 is a gate clock
which enables the RGMII clock output.
This replaces the "m25_div" clock with a clock gate called "m25_en"
which ensures that we can set this bit to 1 whenever we enable RGMII
mode. This however means that we are now missing a "divide by 10" after
the m250_div (and before our new m25_en), otherwise the common clock
framework thinks that the rate of the m25_en clock is 10-times higher
than it is in the actual hardware. That is solved by adding a
fixed-factor clock which divides the m250_div output by 10.
Fixes: 566e8251625304 ("net: stmmac: add a glue driver for the Amlogic Meson 8b
/ GXBB DWMAC")
Reported-by: Emiliano Ingrassia <ingras...@epigenesys.com>
Signed-off-by: Martin Blumenstingl <martin.blumensti...@googlemail.com>
---
.../net/ethernet/stmicro/stmmac/dwmac-meson8b.c | 66 +++++++++++++---------
1 file changed, 38 insertions(+), 28 deletions(-)
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
b/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
index 1c14210df465..7199e8c08536 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
@@ -40,9 +40,7 @@
#define PRG_ETH0_CLK_M250_DIV_SHIFT 7
#define PRG_ETH0_CLK_M250_DIV_WIDTH 3
-/* divides the result of m25_sel by either 5 (bit unset) or 10 (bit set) */
-#define PRG_ETH0_CLK_M25_DIV_SHIFT 10
-#define PRG_ETH0_CLK_M25_DIV_WIDTH 1
+#define PRG_ETH0_GENERATE_25M_PHY_CLOCK 10
#define PRG_ETH0_INVERTED_RMII_CLK BIT(11)
#define PRG_ETH0_TX_AND_PHY_REF_CLK BIT(12)
@@ -63,8 +61,11 @@ struct meson8b_dwmac {
struct clk_divider m250_div;
struct clk *m250_div_clk;
- struct clk_divider m25_div;
- struct clk *m25_div_clk;
+ struct clk_fixed_factor fixed_div10;
+ struct clk *fixed_div10_clk;
+
+ struct clk_gate m25_en;
+ struct clk *m25_en_clk;
u32 tx_delay_ns;
};
@@ -88,11 +89,6 @@ static int meson8b_init_rgmii_clk(struct meson8b_dwmac
*dwmac)
struct device *dev = &dwmac->pdev->dev;
const char *clk_div_parents[1];
const char *mux_parent_names[MUX_CLK_NUM_PARENTS];
- static const struct clk_div_table clk_25m_div_table[] = {
- { .val = 0, .div = 5 },
- { .val = 1, .div = 10 },
- { /* sentinel */ },
- };
/* get the mux parents from DT */
for (i = 0; i < MUX_CLK_NUM_PARENTS; i++) {
@@ -149,25 +145,39 @@ static int meson8b_init_rgmii_clk(struct meson8b_dwmac
*dwmac)
if (WARN_ON(IS_ERR(dwmac->m250_div_clk)))
return PTR_ERR(dwmac->m250_div_clk);
- /* create the m25_div */
- init.name = devm_kasprintf(dev, GFP_KERNEL, "%s#m25_div",
+ /* create the fixed_div10 */
+ init.name = devm_kasprintf(dev, GFP_KERNEL, "%s#fixed_div10",
dev_name(dev));
- init.ops = &clk_divider_ops;
- init.flags = CLK_IS_BASIC | CLK_SET_RATE_PARENT;
+ init.ops = &clk_fixed_factor_ops;
+ init.flags = CLK_SET_RATE_PARENT;
clk_div_parents[0] = __clk_get_name(dwmac->m250_div_clk);
init.parent_names = clk_div_parents;
init.num_parents = ARRAY_SIZE(clk_div_parents);
- dwmac->m25_div.reg = dwmac->regs + PRG_ETH0;
- dwmac->m25_div.shift = PRG_ETH0_CLK_M25_DIV_SHIFT;
- dwmac->m25_div.width = PRG_ETH0_CLK_M25_DIV_WIDTH;
- dwmac->m25_div.table = clk_25m_div_table;
- dwmac->m25_div.hw.init = &init;
- dwmac->m25_div.flags = CLK_DIVIDER_ALLOW_ZERO;
+ dwmac->fixed_div10.mult = 1;
+ dwmac->fixed_div10.div = 10;
+ dwmac->fixed_div10.hw.init = &init;
+
+ dwmac->fixed_div10_clk = devm_clk_register(dev, &dwmac->fixed_div10.hw);
+ if (WARN_ON(IS_ERR(dwmac->fixed_div10_clk)))
+ return PTR_ERR(dwmac->fixed_div10_clk);
+
+ /* create the m25_en */
+ init.name = devm_kasprintf(dev, GFP_KERNEL, "%s#m25_en",
+ dev_name(dev));
+ init.ops = &clk_gate_ops;
+ init.flags = CLK_SET_RATE_PARENT;
+ clk_div_parents[0] = __clk_get_name(dwmac->fixed_div10_clk);
+ init.parent_names = clk_div_parents;
+ init.num_parents = ARRAY_SIZE(clk_div_parents);
+
+ dwmac->m25_en.reg = dwmac->regs + PRG_ETH0;
+ dwmac->m25_en.bit_idx = PRG_ETH0_GENERATE_25M_PHY_CLOCK;
+ dwmac->m25_en.hw.init = &init;
- dwmac->m25_div_clk = devm_clk_register(dev, &dwmac->m25_div.hw);
- if (WARN_ON(IS_ERR(dwmac->m25_div_clk)))
- return PTR_ERR(dwmac->m25_div_clk);
+ dwmac->m25_en_clk = devm_clk_register(dev, &dwmac->m25_en.hw);
+ if (WARN_ON(IS_ERR(dwmac->m25_en_clk)))
+ return PTR_ERR(dwmac->m25_en_clk);
return 0;
}
@@ -200,16 +210,16 @@ static int meson8b_init_prg_eth(struct meson8b_dwmac
*dwmac)
meson8b_dwmac_mask_bits(dwmac, PRG_ETH0, PRG_ETH0_TXDLY_MASK,
tx_dly_val << PRG_ETH0_TXDLY_SHIFT);
- ret = clk_prepare_enable(dwmac->m25_div_clk);
+ ret = clk_prepare_enable(dwmac->m25_en_clk);
if (ret) {
dev_err(&dwmac->pdev->dev, "failed to enable the PHY
clock\n");
return ret;
}
/* Generate the 25MHz RGMII clock for the PHY */
- ret = clk_set_rate(dwmac->m25_div_clk, 25 * 1000 * 1000);
+ ret = clk_set_rate(dwmac->m25_en_clk, 25 * 1000 * 1000);
if (ret) {
- clk_disable_unprepare(dwmac->m25_div_clk);
+ clk_disable_unprepare(dwmac->m25_en_clk);
dev_err(&dwmac->pdev->dev, "failed to set PHY clock\n");
return ret;
@@ -305,7 +315,7 @@ static int meson8b_dwmac_probe(struct platform_device *pdev)
err_clk_disable:
if (phy_interface_mode_is_rgmii(dwmac->phy_mode))
- clk_disable_unprepare(dwmac->m25_div_clk);
+ clk_disable_unprepare(dwmac->m25_en_clk);
err_remove_config_dt:
stmmac_remove_config_dt(pdev, plat_dat);
@@ -317,7 +327,7 @@ static int meson8b_dwmac_remove(struct platform_device
*pdev)
struct meson8b_dwmac *dwmac = get_stmmac_bsp_priv(&pdev->dev);
if (phy_interface_mode_is_rgmii(dwmac->phy_mode))
- clk_disable_unprepare(dwmac->m25_div_clk);
+ clk_disable_unprepare(dwmac->m25_en_clk);
return stmmac_pltfr_remove(pdev);
}
--
2.15.1
