Messages in this thread Patch in this message |  | | From | Gabriel FERNANDEZ <> | Subject | [PATCH v4 6/8] phy: miphy28lp: Add SSC support for PCIE | Date | Wed, 22 Oct 2014 09:14:25 +0200 |
| |
SSC is the technique of modulating the operating frequency of a signal slightly to spread its radiated emissions over a range of frequencies. This reduction in the maximum emission for a given frequency helps meet radiated emission requirements. These settings are applicable for PCIE with Internal clock.
Signed-off-by: Harsh Gupta <harsh.gupta@st.com> Signed-off-by: Gabriel Fernandez <gabriel.fernandez@linaro.org> --- drivers/phy/phy-miphy28lp.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+)
diff --git a/drivers/phy/phy-miphy28lp.c b/drivers/phy/phy-miphy28lp.c index d4569af..ca0d9b4 100644 --- a/drivers/phy/phy-miphy28lp.c +++ b/drivers/phy/phy-miphy28lp.c @@ -192,6 +192,7 @@ #define SATA_SPDMODE 1 #define MIPHY_SATA_BANK_NB 3 +#define MIPHY_PCIE_BANK_NB 2 struct miphy28lp_phy { struct phy *phy; @@ -591,6 +592,46 @@ static void miphy_sata_tune_ssc(struct miphy28lp_phy *miphy_phy) } } +static void miphy_pcie_tune_ssc(struct miphy28lp_phy *miphy_phy) +{ + void __iomem *base = miphy_phy->base; + u8 val; + + /* Compensate Tx impedance to avoid out of range values */ + /* + * Enable the SSC on PLL for all banks + * SSC Modulation @ 31 KHz and 4000 ppm modulation amp + */ + val = readb_relaxed(base + MIPHY_BOUNDARY_2); + val |= SSC_EN_SW; + writeb_relaxed(val, base + MIPHY_BOUNDARY_2); + + val = readb_relaxed(base + MIPHY_BOUNDARY_SEL); + val |= SSC_SEL; + writeb_relaxed(val, base + MIPHY_BOUNDARY_SEL); + + for (val = 0; val < MIPHY_PCIE_BANK_NB; val++) { + writeb_relaxed(val, base + MIPHY_CONF); + + /* Validate Step component */ + writeb_relaxed(0x69, base + MIPHY_PLL_SBR_3); + writeb_relaxed(0x21, base + MIPHY_PLL_SBR_4); + + /* Validate Period component */ + writeb_relaxed(0x3c, base + MIPHY_PLL_SBR_2); + writeb_relaxed(0x21, base + MIPHY_PLL_SBR_4); + + /* Clear any previous request */ + writeb_relaxed(0x00, base + MIPHY_PLL_SBR_1); + + /* requests the PLL to take in account new parameters */ + writeb_relaxed(SET_NEW_CHANGE, base + MIPHY_PLL_SBR_1); + + /* To be sure there is no other pending requests */ + writeb_relaxed(0x00, base + MIPHY_PLL_SBR_1); + } +} + static inline int miphy28lp_configure_sata(struct miphy28lp_phy *miphy_phy) { void __iomem *base = miphy_phy->base; @@ -659,6 +700,9 @@ static inline int miphy28lp_configure_pcie(struct miphy28lp_phy *miphy_phy) if (err) return err; + if (miphy_phy->ssc) + miphy_pcie_tune_ssc(miphy_phy); + return 0; } -- 1.9.1
|  |